diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 378c04b110..614ba34e33 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -292,9 +292,6 @@ jobs:
          #   (https://github.com/ziglang/zig/issues/23576). We therefore
          #   only test the C backend and exclude the native examples.
          # - 0.17 fixes this, so we test the native backends as well.
-         # - The ABI check is not supported with zig: on AArch64 it passes
-         #   -march=armv8-a+simd and -march=armv8.4-a+sha3, which zig rejects
-         #   since it parses -march as a CPU name.
          - family: zig
            version: "0.10"
            shell: zig0_10
@@ -322,7 +319,6 @@ jobs:
            darwin: True
            opt: all
            examples: True
-           extra_args: "--no-abicheck"
     runs-on: ${{ matrix.target.runner }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
diff --git a/.github/workflows/legacy-compilers.yml b/.github/workflows/legacy-compilers.yml
index 2bc0d68616..16c8fc2e64 100644
--- a/.github/workflows/legacy-compilers.yml
+++ b/.github/workflows/legacy-compilers.yml
@@ -194,9 +194,6 @@ jobs:
          #   (https://github.com/ziglang/zig/issues/23576). We therefore
          #   only test the C backend and exclude the native examples.
          # - 0.17 fixes this, so we test the native backends as well.
-         # - The ABI check is not supported with zig: on AArch64 it passes
-         #   -march=armv8-a+simd and -march=armv8.4-a+sha3, which zig rejects
-         #   since it parses -march as a CPU name.
          - family: zig
            version: "0.10"
            shell: zig0_10
@@ -244,7 +241,6 @@ jobs:
            shell: zig0_17
            opt: all
            examples: True
-           extra_args: "--no-abicheck"
     runs-on: ${{ matrix.target.runner }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -435,7 +431,6 @@ jobs:
            shell: zig0_17
            opt: all
            examples: True
-           extra_args: "--no-abicheck"
     runs-on: macos-latest
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
diff --git a/dev/aarch64_clean/src/mlkem_intt_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_intt_aarch64_asm.S
index 2f74cf4cae..79de79e251 100644
--- a/dev/aarch64_clean/src/mlkem_intt_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_intt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -402,5 +403,6 @@ mlk_intt_layer123_start:
     .unreq ninv_tw
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
diff --git a/dev/aarch64_clean/src/mlkem_ntt_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_ntt_aarch64_asm.S
index 1217a31f38..b78a3402cf 100644
--- a/dev/aarch64_clean/src/mlkem_ntt_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_ntt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -341,4 +342,5 @@ mlk_ntt_layer4567_start:
     .unreq t3
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_clean/src/mlkem_poly_mulcache_compute_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_poly_mulcache_compute_aarch64_asm.S
index 7d59bf1ae3..266deee63f 100644
--- a/dev/aarch64_clean/src/mlkem_poly_mulcache_compute_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_poly_mulcache_compute_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -129,4 +130,5 @@ mlk_poly_mulcache_compute_loop_start:
         .unreq modulus_twisted
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_clean/src/mlkem_poly_reduce_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_poly_reduce_aarch64_asm.S
index 1d1847195c..b696069a17 100644
--- a/dev/aarch64_clean/src/mlkem_poly_reduce_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_poly_reduce_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -106,4 +107,5 @@ mlk_poly_reduce_loop_start:
         .unreq modulus_twisted
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_clean/src/mlkem_poly_tobytes_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_poly_tobytes_aarch64_asm.S
index ac28c822de..53eca53f76 100644
--- a/dev/aarch64_clean/src/mlkem_poly_tobytes_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_poly_tobytes_aarch64_asm.S
@@ -28,7 +28,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_KEYPAIR_API) || \
      !defined(MLK_CONFIG_NO_ENCAPS_API))
@@ -96,5 +97,6 @@ mlk_poly_tobytes_loop_start:
         .unreq count
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_KEYPAIR_API || !MLK_CONFIG_NO_ENCAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_KEYPAIR_API || \
+          !MLK_CONFIG_NO_ENCAPS_API) */
diff --git a/dev/aarch64_clean/src/mlkem_poly_tomont_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_poly_tomont_aarch64_asm.S
index cf050fff90..0f8894fbe5 100644
--- a/dev/aarch64_clean/src/mlkem_poly_tomont_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_poly_tomont_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /* simpasm: header-end */
@@ -104,5 +105,5 @@ mlk_poly_tomont_loop:
         .unreq tmp0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
diff --git a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
index 97b4ea1ad7..130a871c08 100644
--- a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
 /* simpasm: header-end */
@@ -256,5 +257,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k2_loop_start:
 
 /* simpasm: footer-start */
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
diff --git a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
index 26b4612bb7..cc2810742e 100644
--- a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
 /* simpasm: header-end */
@@ -259,5 +260,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k3_loop_start:
     .unreq t0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
diff --git a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
index dfc09a075d..42e1bda725 100644
--- a/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
 /* simpasm: header-end */
@@ -269,5 +270,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k4_loop_start:
     .unreq t0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
diff --git a/dev/aarch64_clean/src/mlkem_rej_uniform_aarch64_asm.S b/dev/aarch64_clean/src/mlkem_rej_uniform_aarch64_asm.S
index c0dd83ec77..159c6a83a9 100644
--- a/dev/aarch64_clean/src/mlkem_rej_uniform_aarch64_asm.S
+++ b/dev/aarch64_clean/src/mlkem_rej_uniform_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -461,4 +462,5 @@ mlk_rej_uniform_return:
 #undef STACK_SIZE
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_opt/src/mlkem_intt_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_intt_aarch64_asm.S
index e24c0165e3..b613ec7a55 100644
--- a/dev/aarch64_opt/src/mlkem_intt_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_intt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -1423,5 +1424,6 @@ mlk_intt_layer123_start:
     .unreq ninv_tw
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
diff --git a/dev/aarch64_opt/src/mlkem_ntt_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_ntt_aarch64_asm.S
index 7ce1d5ac16..d30b23321c 100644
--- a/dev/aarch64_opt/src/mlkem_ntt_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_ntt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
 // Bounds:
@@ -1270,4 +1271,5 @@ mlk_ntt_layer4567_start:
     .unreq t3
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_opt/src/mlkem_poly_mulcache_compute_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_poly_mulcache_compute_aarch64_asm.S
index 4143959118..209ad0e27a 100644
--- a/dev/aarch64_opt/src/mlkem_poly_mulcache_compute_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_poly_mulcache_compute_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
 /* Montgomery multiplication, with precomputed Montgomery twist
@@ -279,4 +280,5 @@ mlk_poly_mulcache_compute_loop_start:
         .unreq modulus_twisted
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_opt/src/mlkem_poly_reduce_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_poly_reduce_aarch64_asm.S
index 7db0995d06..8c740e548f 100644
--- a/dev/aarch64_opt/src/mlkem_poly_reduce_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_poly_reduce_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
 /* Barrett reduction */
@@ -332,4 +333,5 @@ mlk_poly_reduce_loop_start:
         .unreq modulus_twisted
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/aarch64_opt/src/mlkem_poly_tobytes_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_poly_tobytes_aarch64_asm.S
index ce4da552bf..3d44923005 100644
--- a/dev/aarch64_opt/src/mlkem_poly_tobytes_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_poly_tobytes_aarch64_asm.S
@@ -28,7 +28,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_KEYPAIR_API) || \
      !defined(MLK_CONFIG_NO_ENCAPS_API))
@@ -256,5 +257,6 @@ mlk_poly_tobytes_loop_start:
         .unreq count
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_KEYPAIR_API || !MLK_CONFIG_NO_ENCAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_KEYPAIR_API || \
+          !MLK_CONFIG_NO_ENCAPS_API) */
diff --git a/dev/aarch64_opt/src/mlkem_poly_tomont_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_poly_tomont_aarch64_asm.S
index 1dd22fb7af..951da09e18 100644
--- a/dev/aarch64_opt/src/mlkem_poly_tomont_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_poly_tomont_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /* simpasm: header-end */
@@ -222,5 +223,5 @@ mlk_poly_tomont_loop:
         .unreq tmp0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
diff --git a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
index 761ed5d0dc..a62d8e745f 100644
--- a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
 /* simpasm: header-end */
 
 // Input:
@@ -586,5 +587,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k2_loop_start:
 
 /* simpasm: footer-start */
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
diff --git a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
index 9294a30d37..306f828089 100644
--- a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
 /* simpasm: header-end */
 
 // Input:
@@ -689,5 +690,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k3_loop_start:
     .unreq t0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
diff --git a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
index 00c947dca2..a2210aa9e2 100644
--- a/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
 /* simpasm: header-end */
 
 // Input:
@@ -799,5 +800,6 @@ mlk_polyvec_basemul_acc_montgomery_cached_k4_loop_start:
     .unreq t0
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
diff --git a/dev/aarch64_opt/src/mlkem_rej_uniform_aarch64_asm.S b/dev/aarch64_opt/src/mlkem_rej_uniform_aarch64_asm.S
index c0dd83ec77..159c6a83a9 100644
--- a/dev/aarch64_opt/src/mlkem_rej_uniform_aarch64_asm.S
+++ b/dev/aarch64_opt/src/mlkem_rej_uniform_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -461,4 +462,5 @@ mlk_rej_uniform_return:
 #undef STACK_SIZE
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S b/dev/fips202/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
index 8143a1e787..307e8bb22d 100644
--- a/dev/fips202/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
+++ b/dev/fips202/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
@@ -33,7 +33,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
+#if defined(MLK_SYS_AARCH64) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -470,5 +471,5 @@ mlk_keccak_f1600_x1_scalar_initial:
 #undef KECCAK_F1600_ROUNDS
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
+#endif /* MLK_SYS_AARCH64 && MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S b/dev/fips202/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
index 949fe79e9c..344300a4f7 100644
--- a/dev/fips202/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
+++ b/dev/fips202/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
@@ -49,10 +49,10 @@
 //
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X1_V84A) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X1_V84A) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 /* simpasm: header-end */
 
 /****************** REGISTER ALLOCATIONS *******************/
@@ -486,7 +486,7 @@ mlk_keccak_f1600_x1_v84a_loop:
 #undef KECCAK_F1600_ROUNDS
 
 /* simpasm: footer-start */
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X1_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X1_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
         */
diff --git a/dev/fips202/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S b/dev/fips202/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
index fa288aa39c..4115cd898d 100644
--- a/dev/fips202/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
+++ b/dev/fips202/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
@@ -49,10 +49,10 @@
 //
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X2_V84A) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X2_V84A) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 /* simpasm: header-end */
 
 /****************** REGISTER ALLOCATIONS *******************/
@@ -432,7 +432,7 @@ mlk_keccak_f1600_x2_v84a_loop:
 #undef KECCAK_F1600_ROUNDS
 
 /* simpasm: footer-start */
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X2_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X2_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
         */
diff --git a/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S b/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
index 9eee8c771d..738b9d5762 100644
--- a/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
+++ b/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
@@ -34,7 +34,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -2580,5 +2581,5 @@ mlk_keccak_f1600_x4_v8a_scalar_hybrid_done:
 #undef STACK_LOC_1
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID && \
-          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID \
+          && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S b/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
index 20edd2d212..43a792db8e 100644
--- a/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
+++ b/dev/fips202/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
@@ -34,10 +34,10 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 /* simpasm: header-end */
 
 #define KECCAK_F1600_ROUNDS 24
@@ -2410,7 +2410,7 @@ mlk_keccak_f1600_x4_v8a_v84a_scalar_hybrid_done:
 #undef STACK_LOC_1
 
 /* simpasm: footer-start */
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64_symbolic/keccak_f1600_x1_scalar_symbolic.S b/dev/fips202/aarch64_symbolic/keccak_f1600_x1_scalar_symbolic.S
index 3f5515b9d0..8fed88c665 100644
--- a/dev/fips202/aarch64_symbolic/keccak_f1600_x1_scalar_symbolic.S
+++ b/dev/fips202/aarch64_symbolic/keccak_f1600_x1_scalar_symbolic.S
@@ -35,7 +35,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
+#if defined(MLK_SYS_AARCH64) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -522,5 +523,5 @@ mlk_keccak_f1600_x1_scalar_end_final:
 #undef KECCAK_F1600_ROUNDS
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
+#endif /* MLK_SYS_AARCH64 && MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_scalar_hybrid_clean.S b/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_scalar_hybrid_clean.S
index dec2e7745a..271ca668ca 100644
--- a/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_scalar_hybrid_clean.S
+++ b/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_scalar_hybrid_clean.S
@@ -33,7 +33,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -1026,5 +1027,5 @@ mlk_keccak_f1600_x4_v8a_scalar_hybrid_done:
 #undef STACK_LOC_1
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID && \
-          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID \
+          && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_v84a_scalar_hybrid_clean.S b/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_v84a_scalar_hybrid_clean.S
index 0631163bb7..d6f3599278 100644
--- a/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_v84a_scalar_hybrid_clean.S
+++ b/dev/fips202/aarch64_symbolic/keccak_f1600_x4_v8a_v84a_scalar_hybrid_clean.S
@@ -34,10 +34,10 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 /* simpasm: header-end */
 
 #define KECCAK_F1600_ROUNDS 24
@@ -1045,7 +1045,7 @@ mlk_keccak_f1600_x4_v8a_v84a_scalar_hybrid_done:
 #undef STACK_LOC_1
 
 /* simpasm: footer-start */
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/armv81m/src/keccak_f1600_x4_mve.S b/dev/fips202/armv81m/src/keccak_f1600_x4_mve.S
index fdeab40d6f..de4254c937 100644
--- a/dev/fips202/armv81m/src/keccak_f1600_x4_mve.S
+++ b/dev/fips202/armv81m/src/keccak_f1600_x4_mve.S
@@ -66,7 +66,8 @@
 //   784     S[0][24]_odd,  S[1][24]_odd,  S[2][24]_odd,  S[3][24]_odd
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -1637,4 +1638,5 @@ mlk_keccak_f1600_x4_mve_asm_roundend:
     .unreq qA20_l
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S b/dev/fips202/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
index d36bae151d..b08f6c82d2 100644
--- a/dev/fips202/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
+++ b/dev/fips202/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
@@ -58,7 +58,8 @@
 //   Tail     -- extract remaining <8 bytes via predicated byte stores.
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -365,4 +366,5 @@ mlk_keccak_f1600_x4_state_extract_bytes_asm_exit:
     .unreq qd3
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S b/dev/fips202/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
index b2069960bf..09fbfc7fc3 100644
--- a/dev/fips202/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
+++ b/dev/fips202/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
@@ -57,7 +57,8 @@
 //   Tail     -- absorb remaining <8 bytes via predicated byte loads.
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /* simpasm: header-end */
 
@@ -420,4 +421,5 @@ mlk_keccak_f1600_x4_state_xor_bytes_asm_exit:
     .unreq qS1
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/fips202/x86_64/src/keccak_f1600_x4_avx2_asm.S b/dev/fips202/x86_64/src/keccak_f1600_x4_avx2_asm.S
index 235ba8e4f1..4be2b08020 100644
--- a/dev/fips202/x86_64/src/keccak_f1600_x4_avx2_asm.S
+++ b/dev/fips202/x86_64/src/keccak_f1600_x4_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 #include "../../../../common.h"
 
-#if defined(MLK_FIPS202_X86_64_NEED_X4_AVX2) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_FIPS202_X86_64_NEED_X4_AVX2) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: keccak_f1600_x4_avx2_asm
@@ -658,4 +659,5 @@ MLK_ASM_FN_SYMBOL(keccak_f1600_x4_avx2_asm)
    ret
 
 /* simpasm: footer-start */
-#endif /* MLK_FIPS202_X86_64_NEED_X4_AVX2 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_FIPS202_X86_64_NEED_X4_AVX2 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/ppc64le/src/mlkem_intt_ppc_asm.S b/dev/ppc64le/src/mlkem_intt_ppc_asm.S
index c702a281dd..b02443d908 100644
--- a/dev/ppc64le/src/mlkem_intt_ppc_asm.S
+++ b/dev/ppc64le/src/mlkem_intt_ppc_asm.S
@@ -7,7 +7,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -1003,5 +1004,6 @@ mlk_intt_ppc_asm_Loopf:
 #undef VS_26_STASH
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
diff --git a/dev/ppc64le/src/mlkem_ntt_ppc_asm.S b/dev/ppc64le/src/mlkem_ntt_ppc_asm.S
index 0319d96bea..946918366b 100644
--- a/dev/ppc64le/src/mlkem_ntt_ppc_asm.S
+++ b/dev/ppc64le/src/mlkem_ntt_ppc_asm.S
@@ -7,7 +7,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: ntt_ppc_asm
@@ -766,5 +767,5 @@ MLK_ASM_FN_SYMBOL(ntt_ppc_asm)
 #undef b4_offset
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/ppc64le/src/mlkem_poly_tomont_ppc_asm.S b/dev/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
index 13e427b4b1..090a80c750 100644
--- a/dev/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
+++ b/dev/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
@@ -14,7 +14,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /*yaml
@@ -241,5 +242,5 @@ MLK_ASM_FN_SYMBOL(poly_tomont_ppc_asm)
 #undef vresult4
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
diff --git a/dev/ppc64le/src/mlkem_reduce_ppc_asm.S b/dev/ppc64le/src/mlkem_reduce_ppc_asm.S
index 1b4e43fabb..8640c6525f 100644
--- a/dev/ppc64le/src/mlkem_reduce_ppc_asm.S
+++ b/dev/ppc64le/src/mlkem_reduce_ppc_asm.S
@@ -6,7 +6,8 @@
  * Written by Danny Tsen <dtsen@us.ibm.com>
  */
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: reduce_ppc_asm
@@ -462,5 +463,5 @@ MLK_ASM_FN_SYMBOL(reduce_ppc_asm)
 #undef vu_q
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_intt_avx2_asm.S b/dev/x86_64/src/mlkem_intt_avx2_asm.S
index 2103947a9c..c3e5307cd8 100644
--- a/dev/x86_64/src/mlkem_intt_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_intt_avx2_asm.S
@@ -29,7 +29,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -315,5 +316,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
diff --git a/dev/x86_64/src/mlkem_ntt_avx2_asm.S b/dev/x86_64/src/mlkem_ntt_avx2_asm.S
index 44568b7d50..729506ca92 100644
--- a/dev/x86_64/src/mlkem_ntt_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_ntt_avx2_asm.S
@@ -25,7 +25,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: ntt_avx2_asm
@@ -267,5 +268,5 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_nttfrombytes_avx2_asm.S b/dev/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
index 0eda6a7767..bbf59d43bb 100644
--- a/dev/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -135,5 +136,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
diff --git a/dev/x86_64/src/mlkem_ntttobytes_avx2_asm.S b/dev/x86_64/src/mlkem_ntttobytes_avx2_asm.S
index 0409dd864b..1b33ae274e 100644
--- a/dev/x86_64/src/mlkem_ntttobytes_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_ntttobytes_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_KEYPAIR_API) || \
      !defined(MLK_CONFIG_NO_ENCAPS_API))
@@ -130,5 +131,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_KEYPAIR_API || !MLK_CONFIG_NO_ENCAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_KEYPAIR_API || \
+          !MLK_CONFIG_NO_ENCAPS_API) */
diff --git a/dev/x86_64/src/mlkem_nttunpack_avx2_asm.S b/dev/x86_64/src/mlkem_nttunpack_avx2_asm.S
index aee8f72f82..512148d855 100644
--- a/dev/x86_64/src/mlkem_nttunpack_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_nttunpack_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: nttunpack_avx2_asm
@@ -99,5 +100,5 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S b/dev/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
index 02fed45bd5..8b94763c89 100644
--- a/dev/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -189,7 +190,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 2 || MLKEM_K == 3) */
diff --git a/dev/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S b/dev/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
index 4e86550354..f33a5b19f9 100644
--- a/dev/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
@@ -31,7 +31,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -161,6 +162,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 4) */
diff --git a/dev/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S b/dev/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
index 719b677de7..f8452af8d5 100644
--- a/dev/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -148,7 +149,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 2 || MLKEM_K == 3) */
diff --git a/dev/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S b/dev/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
index d88f300df1..f2075583ac 100644
--- a/dev/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -167,6 +168,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 4) */
diff --git a/dev/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S b/dev/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
index 1dd99a596d..948ed28674 100644
--- a/dev/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2 || MLKEM_K == 3)
@@ -124,6 +125,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 2 || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
+        */
diff --git a/dev/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S b/dev/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
index 02119511b5..864df84839 100644
--- a/dev/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
@@ -31,7 +31,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
@@ -129,6 +130,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
diff --git a/dev/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S b/dev/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
index 364179ee76..8d68ae981d 100644
--- a/dev/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2 || MLKEM_K == 3)
@@ -121,6 +122,7 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 2 || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
+        */
diff --git a/dev/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S b/dev/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
index 20581d89a4..0a0d2197f9 100644
--- a/dev/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
@@ -30,7 +30,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
@@ -116,6 +117,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
diff --git a/dev/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S b/dev/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
index 16d4b0bd05..ba87773474 100644
--- a/dev/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: poly_mulcache_compute_avx2_asm
@@ -80,5 +81,5 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
index bf1ddff788..c5109eae78 100644
--- a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
 /*yaml
@@ -58,5 +59,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
diff --git a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
index 6152956a57..d6be732c5a 100644
--- a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
 /*yaml
@@ -58,5 +59,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
diff --git a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
index d9538f6efa..68cec1562f 100644
--- a/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
 /*yaml
@@ -58,5 +59,6 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
diff --git a/dev/x86_64/src/mlkem_reduce_avx2_asm.S b/dev/x86_64/src/mlkem_reduce_avx2_asm.S
index af613b406d..17ed795b73 100644
--- a/dev/x86_64/src/mlkem_reduce_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_reduce_avx2_asm.S
@@ -25,7 +25,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: reduce_avx2_asm
@@ -110,5 +111,5 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_rej_uniform_avx2_asm.S b/dev/x86_64/src/mlkem_rej_uniform_avx2_asm.S
index 00ee1b9428..9869e97f87 100644
--- a/dev/x86_64/src/mlkem_rej_uniform_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_rej_uniform_avx2_asm.S
@@ -20,7 +20,8 @@
  **************************************************/
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: rej_uniform_avx2_asm
@@ -209,5 +210,5 @@ mlk_rej_uniform_asm_end:
 #undef STACK_SIZE
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
diff --git a/dev/x86_64/src/mlkem_tomont_avx2_asm.S b/dev/x86_64/src/mlkem_tomont_avx2_asm.S
index 78c359c10c..442635340a 100644
--- a/dev/x86_64/src/mlkem_tomont_avx2_asm.S
+++ b/dev/x86_64/src/mlkem_tomont_avx2_asm.S
@@ -23,7 +23,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /*yaml
@@ -107,5 +108,5 @@ vzeroupper
 ret
 
 /* simpasm: footer-start */
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
diff --git a/integration/aws-lc/pre_import.patch b/integration/aws-lc/pre_import.patch
new file mode 100644
index 0000000000..53715fca17
--- /dev/null
+++ b/integration/aws-lc/pre_import.patch
@@ -0,0 +1,13 @@
+diff --git a/crypto/fipsmodule/ml_kem/importer.sh b/crypto/fipsmodule/ml_kem/importer.sh
+index 6263a90..d582b4c 100644
+--- a/crypto/fipsmodule/ml_kem/importer.sh
++++ b/crypto/fipsmodule/ml_kem/importer.sh
+@@ -146,6 +146,8 @@ for file in $SRC/native/aarch64/src/*.S $SRC/native/x86_64/src/*.S; do
+   # guard collapses and the body is included unconditionally.
+   sed -e ':a' -e 'N' -e '$!ba' -e 's/\\\n/ /g' "$file" | \
+     unifdef -D$backend_define \
++            -DMLK_SYS_AARCH64_NEON \
++            -DMLK_SYS_X86_64_AVX2 \
+             -UMLK_CONFIG_MULTILEVEL_NO_SHARED \
+             -DMLK_CONFIG_MULTILEVEL_WITH_SHARED \
+             -UMLK_CONFIG_NO_KEYPAIR_API \
diff --git a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
index 108e17f83f..8809fa03e5 100644
--- a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
+++ b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_scalar_aarch64_asm.S
@@ -33,7 +33,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
+#if defined(MLK_SYS_AARCH64) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X1_SCALAR) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -369,7 +370,7 @@ Lmlk_keccak_f1600_x1_scalar_loop:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x1_scalar_aarch64_asm)
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
+#endif /* MLK_SYS_AARCH64 && MLK_FIPS202_AARCH64_NEED_X1_SCALAR && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
index cb27677691..4a375fc516 100644
--- a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
+++ b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S
@@ -49,10 +49,10 @@
 //
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X1_V84A) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X1_V84A) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -196,9 +196,9 @@ Lmlk_keccak_f1600_x1_v84a_loop:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x1_v84a_aarch64_asm)
 
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X1_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X1_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
         */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
index 36ebe1d32f..b6a218e353 100644
--- a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
+++ b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S
@@ -49,10 +49,10 @@
 //
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X2_V84A) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X2_V84A) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -251,9 +251,9 @@ Lmlk_keccak_f1600_x2_v84a_loop:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x2_v84a_aarch64_asm)
 
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X2_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X2_V84A && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
         */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
index 7f0f78b340..47cd29237e 100644
--- a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
+++ b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S
@@ -34,7 +34,8 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -1071,8 +1072,8 @@ Lmlk_keccak_f1600_x4_v8a_scalar_hybrid_done:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm)
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID && \
-          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_FIPS202_AARCH64_NEED_X4_V8A_SCALAR_HYBRID \
+          && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
index c17267c605..79d41f30b3 100644
--- a/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
+++ b/mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
@@ -34,10 +34,10 @@
 */
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
+#if defined(MLK_SYS_AARCH64_NEON) && defined(__ARM_FEATURE_SHA3) && \
+    defined(MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
-#if defined(__ARM_FEATURE_SHA3)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -979,9 +979,9 @@ Lmlk_keccak_f1600_x4_v8a_v84a_scalar_hybrid_done:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm)
 
-#endif /* __ARM_FEATURE_SHA3 */
 
-#endif /* MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
+#endif /* MLK_SYS_AARCH64_NEON && __ARM_FEATURE_SHA3 && \
+          MLK_FIPS202_AARCH64_NEED_X4_V8A_V84A_SCALAR_HYBRID && \
           !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_mve.S b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_mve.S
index 2bf6c3ec18..2ed34e9ce1 100644
--- a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_mve.S
+++ b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_mve.S
@@ -66,7 +66,8 @@
 //   784     S[0][24]_odd,  S[1][24]_odd,  S[2][24]_odd,  S[3][24]_odd
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -709,7 +710,8 @@ Lmlk_keccak_f1600_x4_mve_asm_roundend:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_mve_asm)
 
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
index 398f58f4d5..d495f8293d 100644
--- a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
+++ b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S
@@ -58,7 +58,8 @@
 //   Tail     -- extract remaining <8 bytes via predicated byte stores.
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -343,7 +344,8 @@ Lmlk_keccak_f1600_x4_state_extract_bytes_asm_exit:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_state_extract_bytes_asm)
 
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
index 3f1b852bbe..dbdabf53ff 100644
--- a/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
+++ b/mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S
@@ -57,7 +57,8 @@
 //   Tail     -- absorb remaining <8 bytes via predicated byte loads.
 
 #include "../../../../common.h"
-#if defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
+#if defined(MLK_SYS_ARMV81M_MVE) && \
+    defined(MLK_FIPS202_ARMV81M_NEED_X4) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -364,7 +365,8 @@ Lmlk_keccak_f1600_x4_state_xor_bytes_asm_exit:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_state_xor_bytes_asm)
 
-#endif /* MLK_FIPS202_ARMV81M_NEED_X4 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_ARMV81M_MVE && MLK_FIPS202_ARMV81M_NEED_X4 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/fips202/native/x86_64/src/keccak_f1600_x4_avx2_asm.S b/mlkem/src/fips202/native/x86_64/src/keccak_f1600_x4_avx2_asm.S
index 6d1504bd5f..3d5ac10ef0 100644
--- a/mlkem/src/fips202/native/x86_64/src/keccak_f1600_x4_avx2_asm.S
+++ b/mlkem/src/fips202/native/x86_64/src/keccak_f1600_x4_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 #include "../../../../common.h"
 
-#if defined(MLK_FIPS202_X86_64_NEED_X4_AVX2) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_FIPS202_X86_64_NEED_X4_AVX2) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: keccak_f1600_x4_avx2_asm
@@ -481,7 +482,8 @@ LLmlk_keccak_f1600_x4_avx2:
 
 MLK_ASM_FN_SIZE(keccak_f1600_x4_avx2_asm)
 
-#endif /* MLK_FIPS202_X86_64_NEED_X4_AVX2 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_FIPS202_X86_64_NEED_X4_AVX2 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_intt_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_intt_aarch64_asm.S
index 0901957893..8edd07f134 100644
--- a/mlkem/src/native/aarch64/src/mlkem_intt_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_intt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -627,8 +628,9 @@ Lmlk_intt_layer123_start:
 
 MLK_ASM_FN_SIZE(intt_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_ntt_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_ntt_aarch64_asm.S
index 2383c0f05e..0b63ad0da2 100644
--- a/mlkem/src/native/aarch64/src/mlkem_ntt_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_ntt_aarch64_asm.S
@@ -51,7 +51,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -558,7 +559,8 @@ Lmlk_ntt_layer4567_start:
 
 MLK_ASM_FN_SIZE(ntt_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_poly_mulcache_compute_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_poly_mulcache_compute_aarch64_asm.S
index 4b869f8c92..91953e7c59 100644
--- a/mlkem/src/native/aarch64/src/mlkem_poly_mulcache_compute_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_poly_mulcache_compute_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -123,7 +124,8 @@ Lmlk_poly_mulcache_compute_loop_start:
 
 MLK_ASM_FN_SIZE(poly_mulcache_compute_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_poly_reduce_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_poly_reduce_aarch64_asm.S
index 0244ac6af3..a348ff9907 100644
--- a/mlkem/src/native/aarch64/src/mlkem_poly_reduce_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_poly_reduce_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -146,7 +147,8 @@ Lmlk_poly_reduce_loop_start:
 
 MLK_ASM_FN_SIZE(poly_reduce_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_poly_tobytes_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_poly_tobytes_aarch64_asm.S
index 57b798c171..8c30cc7506 100644
--- a/mlkem/src/native/aarch64/src/mlkem_poly_tobytes_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_poly_tobytes_aarch64_asm.S
@@ -28,7 +28,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_KEYPAIR_API) || \
      !defined(MLK_CONFIG_NO_ENCAPS_API))
@@ -116,8 +117,9 @@ Lmlk_poly_tobytes_loop_start:
 
 MLK_ASM_FN_SIZE(poly_tobytes_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          (!MLK_CONFIG_NO_KEYPAIR_API || !MLK_CONFIG_NO_ENCAPS_API) */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_KEYPAIR_API || \
+          !MLK_CONFIG_NO_ENCAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_poly_tomont_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_poly_tomont_aarch64_asm.S
index 9179e3ff94..5279ce74cc 100644
--- a/mlkem/src/native/aarch64/src/mlkem_poly_tomont_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_poly_tomont_aarch64_asm.S
@@ -22,7 +22,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 
@@ -94,8 +95,8 @@ Lmlk_poly_tomont_loop:
 
 MLK_ASM_FN_SIZE(poly_tomont_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
-          !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
index 41bd1581ed..2003f18aaf 100644
--- a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -256,7 +257,8 @@ Lmlk_polyvec_basemul_acc_montgomery_cached_k2_loop_start:
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm)
 
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
index 7dcc8aead2..2ccb14e77c 100644
--- a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -309,7 +310,8 @@ Lmlk_polyvec_basemul_acc_montgomery_cached_k3_loop_start:
 
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
index 5d1ff00e94..921749ec14 100644
--- a/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S
@@ -52,7 +52,8 @@
 /* Re-implementation of asymmetric base multiplication following @[NeonNTT] */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) &&  !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) &&  (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
 
 /*
  * WARNING: This file is auto-derived from the mlkem-native source file
@@ -363,7 +364,8 @@ Lmlk_polyvec_basemul_acc_montgomery_cached_k4_loop_start:
 
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
           (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
 
 #if defined(__ELF__)
diff --git a/mlkem/src/native/aarch64/src/mlkem_rej_uniform_aarch64_asm.S b/mlkem/src/native/aarch64/src/mlkem_rej_uniform_aarch64_asm.S
index 8ba4081485..45040f7249 100644
--- a/mlkem/src/native/aarch64/src/mlkem_rej_uniform_aarch64_asm.S
+++ b/mlkem/src/native/aarch64/src/mlkem_rej_uniform_aarch64_asm.S
@@ -40,7 +40,8 @@
 */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_AARCH64) && \
+#if defined(MLK_SYS_AARCH64_NEON) && \
+    defined(MLK_ARITH_BACKEND_AARCH64) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 
 /*
@@ -219,7 +220,8 @@ Lmlk_rej_uniform_return:
 
 MLK_ASM_FN_SIZE(rej_uniform_aarch64_asm)
 
-#endif /* MLK_ARITH_BACKEND_AARCH64 && !MLK_CONFIG_MULTILEVEL_NO_SHARED */
+#endif /* MLK_SYS_AARCH64_NEON && MLK_ARITH_BACKEND_AARCH64 && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/ppc64le/src/mlkem_intt_ppc_asm.S b/mlkem/src/native/ppc64le/src/mlkem_intt_ppc_asm.S
index e665bc0da2..a40b0e91a4 100644
--- a/mlkem/src/native/ppc64le/src/mlkem_intt_ppc_asm.S
+++ b/mlkem/src/native/ppc64le/src/mlkem_intt_ppc_asm.S
@@ -7,7 +7,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -3237,8 +3238,9 @@ mlk_intt_ppc_asm_Loopf:
 
 MLK_ASM_FN_SIZE(intt_ppc_asm)
 
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/ppc64le/src/mlkem_ntt_ppc_asm.S b/mlkem/src/native/ppc64le/src/mlkem_ntt_ppc_asm.S
index cd9c7b810a..8ac59efce4 100644
--- a/mlkem/src/native/ppc64le/src/mlkem_ntt_ppc_asm.S
+++ b/mlkem/src/native/ppc64le/src/mlkem_ntt_ppc_asm.S
@@ -7,7 +7,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: ntt_ppc_asm
@@ -1664,8 +1665,8 @@ MLK_ASM_FN_SYMBOL(ntt_ppc_asm)
 
 MLK_ASM_FN_SIZE(ntt_ppc_asm)
 
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/ppc64le/src/mlkem_poly_tomont_ppc_asm.S b/mlkem/src/native/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
index 7a9be58fa3..e80f99aa05 100644
--- a/mlkem/src/native/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
+++ b/mlkem/src/native/ppc64le/src/mlkem_poly_tomont_ppc_asm.S
@@ -14,7 +14,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /*yaml
@@ -308,8 +309,8 @@ MLK_ASM_FN_SYMBOL(poly_tomont_ppc_asm)
 
 MLK_ASM_FN_SIZE(poly_tomont_ppc_asm)
 
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/ppc64le/src/mlkem_reduce_ppc_asm.S b/mlkem/src/native/ppc64le/src/mlkem_reduce_ppc_asm.S
index c3fffcf3f4..e690f65268 100644
--- a/mlkem/src/native/ppc64le/src/mlkem_reduce_ppc_asm.S
+++ b/mlkem/src/native/ppc64le/src/mlkem_reduce_ppc_asm.S
@@ -6,7 +6,8 @@
  * Written by Danny Tsen <dtsen@us.ibm.com>
  */
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
+#if defined(MLK_SYS_PPC64LE_POWER8_VECTOR) && \
+    defined(MLK_ARITH_BACKEND_PPC64LE_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: reduce_ppc_asm
@@ -723,8 +724,8 @@ MLK_ASM_FN_SYMBOL(reduce_ppc_asm)
 
 MLK_ASM_FN_SIZE(reduce_ppc_asm)
 
-#endif /* MLK_ARITH_BACKEND_PPC64LE_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_PPC64LE_POWER8_VECTOR && MLK_ARITH_BACKEND_PPC64LE_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_intt_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_intt_avx2_asm.S
index a1b915d924..5bf514a194 100644
--- a/mlkem/src/native/x86_64/src/mlkem_intt_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_intt_avx2_asm.S
@@ -29,7 +29,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -736,8 +737,9 @@ MLK_ASM_FN_SYMBOL(invntt_avx2_asm)
 
 MLK_ASM_FN_SIZE(invntt_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_ntt_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_ntt_avx2_asm.S
index 96897b8f90..921549b6b3 100644
--- a/mlkem/src/native/x86_64/src/mlkem_ntt_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_ntt_avx2_asm.S
@@ -25,7 +25,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: ntt_avx2_asm
@@ -654,8 +655,8 @@ MLK_ASM_FN_SYMBOL(ntt_avx2_asm)
 
 MLK_ASM_FN_SIZE(ntt_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_nttfrombytes_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
index 6e02c1a76a..69269e76d8 100644
--- a/mlkem/src/native/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_nttfrombytes_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API))
@@ -210,8 +211,9 @@ MLK_ASM_FN_SYMBOL(nttfrombytes_avx2_asm)
 
 MLK_ASM_FN_SIZE(nttfrombytes_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_ntttobytes_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_ntttobytes_avx2_asm.S
index 4755d236ad..c6a49f4e07 100644
--- a/mlkem/src/native/x86_64/src/mlkem_ntttobytes_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_ntttobytes_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_KEYPAIR_API) || \
      !defined(MLK_CONFIG_NO_ENCAPS_API))
@@ -198,8 +199,9 @@ MLK_ASM_FN_SYMBOL(ntttobytes_avx2_asm)
 
 MLK_ASM_FN_SIZE(ntttobytes_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_KEYPAIR_API || !MLK_CONFIG_NO_ENCAPS_API) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_KEYPAIR_API || \
+          !MLK_CONFIG_NO_ENCAPS_API) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_nttunpack_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_nttunpack_avx2_asm.S
index ff781ee505..c96d98fef9 100644
--- a/mlkem/src/native/x86_64/src/mlkem_nttunpack_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_nttunpack_avx2_asm.S
@@ -19,7 +19,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: nttunpack_avx2_asm
@@ -183,8 +184,8 @@ MLK_ASM_FN_SYMBOL(nttunpack_avx2_asm)
 
 MLK_ASM_FN_SIZE(nttunpack_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
index a069501bdc..d733462799 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -404,10 +405,10 @@ MLK_ASM_FN_SYMBOL(poly_compress_d10_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_compress_d10_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 2 || MLKEM_K == 3) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
index f78225b803..4ad822291e 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S
@@ -31,7 +31,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -471,9 +472,10 @@ MLK_ASM_FN_SYMBOL(poly_compress_d11_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_compress_d11_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 4) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
index 1e509e129a..000947ae69 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -185,10 +186,10 @@ MLK_ASM_FN_SYMBOL(poly_compress_d4_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_compress_d4_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 2 || MLKEM_K == 3) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
index e85fc1148c..5fc50b9a55 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (!defined(MLK_CONFIG_NO_ENCAPS_API) || \
      !defined(MLK_CONFIG_NO_DECAPS_API)) && \
@@ -243,9 +244,10 @@ MLK_ASM_FN_SYMBOL(poly_compress_d5_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_compress_d5_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (!MLK_CONFIG_NO_ENCAPS_API || !MLK_CONFIG_NO_DECAPS_API) && \
-          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && (!MLK_CONFIG_NO_ENCAPS_API || \
+          !MLK_CONFIG_NO_DECAPS_API) && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
+          MLKEM_K == 4) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
index 6cfdc3ec0a..5b5a4b5ac6 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2 || MLKEM_K == 3)
@@ -249,9 +250,10 @@ MLK_ASM_FN_SYMBOL(poly_decompress_d10_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_decompress_d10_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 2 || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
+        */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
index fe8d13d0ec..128696d5a5 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S
@@ -31,7 +31,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
@@ -299,9 +300,9 @@ MLK_ASM_FN_SYMBOL(poly_decompress_d11_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_decompress_d11_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
index 1e441c9b6a..0fbdf1b844 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S
@@ -29,7 +29,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2 || MLKEM_K == 3)
@@ -201,9 +202,10 @@ MLK_ASM_FN_SYMBOL(poly_decompress_d4_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_decompress_d4_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 2 || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2 || MLKEM_K == 3) \
+        */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
index fe2df3c1fe..4680c6401a 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S
@@ -30,7 +30,8 @@
  **************************************************/
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_DECAPS_API) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
@@ -214,9 +215,9 @@ MLK_ASM_FN_SYMBOL(poly_decompress_d5_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_decompress_d5_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_DECAPS_API && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || \
-          MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_DECAPS_API && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
index 42b331ef3f..a78e495158 100644
--- a/mlkem/src/native/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: poly_mulcache_compute_avx2_asm
@@ -111,8 +112,8 @@ MLK_ASM_FN_SYMBOL(poly_mulcache_compute_avx2_asm)
 
 MLK_ASM_FN_SIZE(poly_mulcache_compute_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
index 1e72e9ecca..e70acbb441 100644
--- a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 2)
 /*yaml
@@ -529,8 +530,9 @@ MLK_ASM_FN_SYMBOL(polyvec_basemul_acc_montgomery_cached_k2_avx2_asm)
 
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k2_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 2) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
index 4cb8dc92d8..232e0d288c 100644
--- a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 3)
 /*yaml
@@ -777,8 +778,9 @@ MLK_ASM_FN_SYMBOL(polyvec_basemul_acc_montgomery_cached_k3_avx2_asm)
 
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k3_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 3) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
index a7aada7e5a..ebb48be2b3 100644
--- a/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S
@@ -4,7 +4,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     (defined(MLK_CONFIG_MULTILEVEL_WITH_SHARED) || MLKEM_K == 4)
 /*yaml
@@ -1025,8 +1026,9 @@ MLK_ASM_FN_SYMBOL(polyvec_basemul_acc_montgomery_cached_k4_avx2_asm)
 
 MLK_ASM_FN_SIZE(polyvec_basemul_acc_montgomery_cached_k4_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && \
+          (MLK_CONFIG_MULTILEVEL_WITH_SHARED || MLKEM_K == 4) */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_reduce_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_reduce_avx2_asm.S
index 29ea77e754..b540c059b7 100644
--- a/mlkem/src/native/x86_64/src/mlkem_reduce_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_reduce_avx2_asm.S
@@ -25,7 +25,8 @@
 
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: reduce_avx2_asm
@@ -227,8 +228,8 @@ MLK_ASM_FN_SYMBOL(reduce_avx2_asm)
 
 MLK_ASM_FN_SIZE(reduce_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_rej_uniform_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_rej_uniform_avx2_asm.S
index 18ed1c8df1..a6ccf4aead 100644
--- a/mlkem/src/native/x86_64/src/mlkem_rej_uniform_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_rej_uniform_avx2_asm.S
@@ -20,7 +20,8 @@
  **************************************************/
 #include "../../../common.h"
 
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED)
 /*yaml
   Name: rej_uniform_avx2_asm
@@ -128,8 +129,8 @@ Lmlk_rej_uniform_asm_end:
 
 MLK_ASM_FN_SIZE(rej_uniform_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-        */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/native/x86_64/src/mlkem_tomont_avx2_asm.S b/mlkem/src/native/x86_64/src/mlkem_tomont_avx2_asm.S
index 144c2218d9..710b6351da 100644
--- a/mlkem/src/native/x86_64/src/mlkem_tomont_avx2_asm.S
+++ b/mlkem/src/native/x86_64/src/mlkem_tomont_avx2_asm.S
@@ -23,7 +23,8 @@
  */
 
 #include "../../../common.h"
-#if defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
+#if defined(MLK_SYS_X86_64_AVX2) && \
+    defined(MLK_ARITH_BACKEND_X86_64_DEFAULT) && \
     !defined(MLK_CONFIG_MULTILEVEL_NO_SHARED) && \
     !defined(MLK_CONFIG_NO_KEYPAIR_API)
 /*yaml
@@ -165,8 +166,8 @@ MLK_ASM_FN_SYMBOL(tomont_avx2_asm)
 
 MLK_ASM_FN_SIZE(tomont_avx2_asm)
 
-#endif /* MLK_ARITH_BACKEND_X86_64_DEFAULT && !MLK_CONFIG_MULTILEVEL_NO_SHARED \
-          && !MLK_CONFIG_NO_KEYPAIR_API */
+#endif /* MLK_SYS_X86_64_AVX2 && MLK_ARITH_BACKEND_X86_64_DEFAULT && \
+          !MLK_CONFIG_MULTILEVEL_NO_SHARED && !MLK_CONFIG_NO_KEYPAIR_API */
 
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
diff --git a/mlkem/src/sys.h b/mlkem/src/sys.h
index 5b65630106..41a9420bbc 100644
--- a/mlkem/src/sys.h
+++ b/mlkem/src/sys.h
@@ -57,8 +57,9 @@
 #define MLK_SYS_AARCH64_EB
 #endif
 
-/* Check if we're running on an Armv8.1-M system with MVE */
-#if defined(__ARM_ARCH_8_1M_MAIN__) || defined(__ARM_FEATURE_MVE)
+/* Check if the Armv8.1-M compilation target supports MVE. Armv8.1-M
+ * architecture support alone does not imply that MVE is enabled. */
+#if defined(__ARM_FEATURE_MVE)
 #define MLK_SYS_ARMV81M_MVE
 #endif
 
diff --git a/scripts/autogen b/scripts/autogen
index cf47c21a8e..32514d63a0 100755
--- a/scripts/autogen
+++ b/scripts/autogen
@@ -3358,25 +3358,6 @@ def gen_hol_light_asm_file(job):
     )
 
 
-# Map dev/ source directory to the corresponding upstream under mlkem/.
-def upstream_src_dir_for_dev_dir(dev_dir):
-    if dev_dir.startswith("dev/fips202/"):
-        # dev/fips202/<arch>/src -> mlkem/src/fips202/native/<arch>/src
-        arch = dev_dir.split("/")[2]
-        return f"mlkem/src/fips202/native/{arch}/src"
-    if dev_dir.startswith("dev/aarch64_"):
-        # dev/aarch64_opt/src and dev/aarch64_clean/src map to the same tree
-        return "mlkem/src/native/aarch64/src"
-    if dev_dir.startswith("dev/x86_64/"):
-        return "mlkem/src/native/x86_64/src"
-    if dev_dir.startswith("dev/ppc64le/"):
-        return "mlkem/src/native/ppc64le/src"
-    raise ValueError(
-        f"Unrecognised dev/ source directory {dev_dir!r}; "
-        "extend upstream_src_dir_for_dev_dir() to map it to mlkem/src/..."
-    )
-
-
 def hol_light_asm_joblist():
     """Return the list of simpasm export jobs, each (basename, dev_dir, cflags,
     arch). Consumed by the HOL-Light assembly copies (gen_hol_light_asm) and, as
@@ -3788,13 +3769,15 @@ def synchronize_backends(
         # comparing the object code before and after simplification.
         cflags="-Idev/x86_64/src/ -Imlkem/src/native/x86_64/src/ -mavx2 -mbmi2 -msse4 -fcf-protection=none",
     )
+    # GCC exposes __ARM_FEATURE_MVE only with a softfp or hard float ABI.
+    # The assembly feature guards must see MVE while regenerating kernels.
     synchronize_backend(
         "dev/fips202/armv81m/src",
         "mlkem/src/fips202/native/armv81m/src",
         delete=delete,
         force_cross=force_cross,
         no_simplify=no_simplify,
-        cflags="-Idev/fips202/armv81m/src -Imlkem/src/fips202/native/armv81m/src -march=armv8.1-m.main+mve -mthumb",
+        cflags="-Idev/fips202/armv81m/src -Imlkem/src/fips202/native/armv81m/src -march=armv8.1-m.main+mve -mthumb -mfloat-abi=hard",
     )
     synchronize_backend(
         "dev/fips202/armv81m",
@@ -3802,7 +3785,7 @@ def synchronize_backends(
         delete=delete,
         force_cross=force_cross,
         no_simplify=no_simplify,
-        cflags="-Idev/fips202/armv81m -Imlkem/src/fips202/native/armv81m -march=armv8.1-m.main+mve -mthumb",
+        cflags="-Idev/fips202/armv81m -Imlkem/src/fips202/native/armv81m -march=armv8.1-m.main+mve -mthumb -mfloat-abi=hard",
     )
     synchronize_backend(
         "dev/fips202/x86_64/src",
@@ -4865,71 +4848,37 @@ def extract_yaml_from_assembly(assembly_file):
 # ABI checker capability table.
 #
 # Maps each `ABI.Features:` tag from the kernel YAMLs to:
-#   - 'asm_subdir':  the arch this cap belongs to; selects the per-arch
-#                    test/abicheck/<asm_subdir>/abicheck_<asm_subdir>.mk it is
-#                    emitted into.
 #   - 'guard':       if non-None, wrap the generated check in #if defined(...).
 #   - 'syscap':      runtime capability; check skips if the host lacks it.
-#   - 'cflags':      for the autogeneration of the per-arch abicheck_<arch>.mk.
 #   - 'description': shown when a check is skipped.
-#   - 'aux_files':   extra .S files needing these CFLAGS though not generated
-#                    kernel exports (hand-written abicheck stubs/selftests, and
-#                    sources whose YAML doesn't list them as ABI-tested kernels
-#                    but still need the per-cap toolchain flags).
 ABI_CAPS = {
     "AVX2": {
-        "asm_subdir": "x86_64",
-        "guard": "__AVX2__",
+        "guard": "MLK_SYS_X86_64_AVX2",
         "syscap": "MLK_SYS_CAP_X86_64_AVX2",
         "description": "AVX2",
-        "cflags": ["-mavx2", "-mbmi2"],
-        "aux_files": [],
     },
     "NEON": {
-        "asm_subdir": "aarch64",
         "guard": "MLK_SYS_AARCH64_NEON",
         "syscap": "MLK_SYS_CAP_AARCH64_NEON",
         "description": "AArch64 NEON",
-        "cflags": ["-march=armv8-a+simd"],
-        "aux_files": [],
     },
     "SHA3": {
-        "asm_subdir": "aarch64",
         "guard": "__ARM_FEATURE_SHA3",
         "syscap": "MLK_SYS_CAP_AARCH64_SHA3",
         "description": "Armv8.4-A SHA3 (eor3, rax1, xar, bcax)",
-        "cflags": ["-march=armv8.4-a+sha3"],
-        "aux_files": [],
     },
     "MVE": {
-        "asm_subdir": "armv81m",
-        "guard": "__ARM_FEATURE_MVE",
+        "guard": "MLK_SYS_ARMV81M_MVE",
         "syscap": "MLK_SYS_CAP_ARMV81M_MVE",
         "description": "Armv8.1-M MVE",
-        "cflags": ["-march=armv8.1-m.main+mve", "-mthumb"],
-        "aux_files": [
-            "test/abicheck/armv81m/callstub_armv81m.S",
-            "test/abicheck/armv81m/selftest_armv81m.S",
-            # Shipped MVE helpers pulled in by the abicheck wildcard but
-            # not registered as ABI-tested kernels - they still need MVE
-            # CFLAGS to assemble.
-            "mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S",
-            "mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S",
-        ],
     },
     # NTT/INTT use the POWER8 vector merges vmrgew/vmrgow (ISA 2.07).
     # AltiVec predates POWER8, and VSX was introduced in POWER7.
     # All current PPC64 kernels and ABI stubs share the backend's guard.
     "POWER8_VECTOR": {
-        "asm_subdir": "ppc64le",
         "guard": "MLK_SYS_PPC64LE_POWER8_VECTOR",
         "syscap": "MLK_SYS_CAP_PPC64LE_POWER8_VECTOR",
         "description": "AltiVec/VSX and POWER8 vector extensions (Power ISA 2.07)",
-        "cflags": ["-mcpu=power8", "-maltivec", "-mvsx"],
-        "aux_files": [
-            "test/abicheck/ppc64le/callstub_ppc64le.S",
-            "test/abicheck/ppc64le/selftest_ppc64le.S",
-        ],
     },
 }
 
@@ -5113,10 +5062,6 @@ def gen_abicheck():
     # Bucket joblist entries by their YAML-declared (arch, calling) pair so a
     # single dev source file is fully self-describing.
     jobs_by_arch_calling = {key: [] for key in ARCH_CALLINGS}
-    # Map cap -> sorted list of .S files that require it. Drives the
-    # generated per-arch abicheck_<arch>.mk at the end of this function.
-    cap_to_files = {cap: [] for cap in ABI_CAPS}
-
     for entry in sorted(joblist, key=lambda j: j[0]):
         assembly_basename, dev_src_dir, _cflags, joblist_arch = entry
         dev_source = f"{dev_src_dir}/{assembly_basename}"
@@ -5128,9 +5073,6 @@ def gen_abicheck():
                 f"{dev_source}: YAML 'ABI.Architecture: {arch_calling[0]}' "
                 f"disagrees with joblist arch {joblist_arch!r}"
             )
-        upstream_src_dir = upstream_src_dir_for_dev_dir(dev_src_dir)
-        for cap in kernel_features(yaml_data, dev_source):
-            cap_to_files[cap].append(f"{upstream_src_dir}/{assembly_basename}")
         jobs_by_arch_calling[arch_calling].append((entry, yaml_data))
 
     # Per-(arch, calling) generated metadata used to assemble checks_all.h:
@@ -5155,12 +5097,14 @@ def gen_abicheck():
             features = kernel_features(yaml_data, dev_source)
             registers = kernel_registers(yaml_data, dev_source)
             # Compile-time guards derived from Features. Each capability with a
-            # 'guard' (e.g. __AVX2__ for AVX2, __ARM_FEATURE_SHA3 for SHA3)
+            # 'guard' (e.g. MLK_SYS_X86_64_AVX2 for AVX2)
             # contributes an #if term mirroring the backend's own compile-time
             # gate; runtime gating via mlk_sys_check_capability is
             # additional, not a replacement.
             feature_guards = [
-                ABI_CAPS[f]["guard"] for f in features if ABI_CAPS[f]["guard"]
+                ABI_CAPS[f]["guard"]
+                for f in features
+                if ABI_CAPS[f]["guard"] and ABI_CAPS[f]["guard"] != arch_guard
             ]
 
             function_name = yaml_data.get("Name")
@@ -5360,7 +5304,7 @@ def gen_abicheck():
         # Emit one row per function, consolidating consecutive functions that
         # share the same feature_guards into a single #if/#endif block (rather
         # than one block per function). This collapses a uniform-feature group
-        # (e.g. x86_64, where every kernel is gated on __AVX2__) into a single
+        # (e.g. x86_64, where every kernel requires AVX2) into a single
         # block, while still splitting where guards differ (e.g. aarch64, where
         # SHA3 and non-SHA3 kernels are interleaved).
         def emit_feature_grouped(functions, render):
@@ -5425,72 +5369,6 @@ def gen_abicheck():
             force_format=True,
         )
 
-    # Emit per-capability CFLAGS injection for the build, split per arch:
-    # one test/abicheck/<arch>/abicheck_<arch>.mk per arch with caps, plus a
-    # top-level test/abicheck/abicheck.mk that includes them all. Single source
-    # of truth alongside the C-time guard (arch_flags) and runtime cap check.
-    caps_by_subdir = {}
-    for cap in sorted(ABI_CAPS):
-        caps_by_subdir.setdefault(ABI_CAPS[cap]["asm_subdir"], []).append(cap)
-
-    def gen_features_mk(asm_subdir, caps):
-        yield from gen_yaml_header()
-        yield from gen_yaml_autogen_warning()
-        yield "#"
-        yield "# Edit the YAML 'ABI.Features:' list in dev/<arch>/src/<kernel>.S"
-        yield "# and re-run scripts/autogen instead."
-        yield "#"
-        yield "# For each capability declared by a kernel's ABI.Features list, this"
-        yield "# file appends the capability's CFLAGS to that kernel's .S object"
-        yield "# under mlkem/src/."
-        yield ""
-        yield "# Default each cap's file list to empty so the unconditional appends"
-        yield "# below are safe even when a cap has no kernels on this arch."
-        for cap in caps:
-            yield f"ABICHECK_REQ_{cap}_FILES :="
-        for cap in caps:
-            # Files needing this cap's CFLAGS are: the kernel exports declared
-            # by YAML, plus any always-on auxiliary files (callstub/selftest)
-            # listed in ABI_CAPS[cap]['aux_files'].
-            files = sorted(
-                set(cap_to_files[cap]) | set(ABI_CAPS[cap].get("aux_files", []))
-            )
-            if not files:
-                continue
-            cflags = " ".join(ABI_CAPS[cap]["cflags"])
-            yield ""
-            yield f"# {cap}: {ABI_CAPS[cap]['description']}"
-            yield f"ABICHECK_REQ_{cap}_FILES := \\"
-            for i, f in enumerate(files):
-                sep = " \\" if i + 1 < len(files) else ""
-                yield f"  {f}{sep}"
-            yield (
-                f"ABICHECK_REQ_{cap}_OBJS := "
-                f"$(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_{cap}_FILES))"
-            )
-            if cflags:
-                yield f"$(ABICHECK_REQ_{cap}_OBJS): CFLAGS += {cflags}"
-        yield ""
-
-    for asm_subdir, caps in caps_by_subdir.items():
-        update_file(
-            f"test/abicheck/{asm_subdir}/abicheck_{asm_subdir}.mk",
-            "\n".join(gen_features_mk(asm_subdir, caps)),
-        )
-
-    def gen_abicheck_mk():
-        yield from gen_yaml_header()
-        yield from gen_yaml_autogen_warning()
-        yield "#"
-        yield "# Includes the per-arch abicheck_<arch>.mk, each of which appends"
-        yield "# its capabilities' CFLAGS to the matching .S objects."
-        yield ""
-        for asm_subdir in sorted(caps_by_subdir):
-            yield f"include test/abicheck/{asm_subdir}/abicheck_{asm_subdir}.mk"
-        yield ""
-
-    update_file("test/abicheck/abicheck.mk", "\n".join(gen_abicheck_mk()))
-
 
 def _main():
     slothy_choices = [
diff --git a/test/abicheck/README.md b/test/abicheck/README.md
index c83e1a13f7..1b545ca2f7 100644
--- a/test/abicheck/README.md
+++ b/test/abicheck/README.md
@@ -31,8 +31,9 @@ Before trusting any verdict, `abicheck.c` runs a self-test: hand-written
 corrupters (`<arch>/selftest_<arch>.S`) that each clobber one callee-saved
 register, confirming the checker fires.
 
-The `mlkem/src/.../*.S` sources are assembled directly. Compile-time feature
-guards select which checks are registered; a check is skipped if
+The `mlkem/src/.../*.S` sources are assembled directly with the build's CPU
+flags. Their system capability guards omit code for unsupported features. Matching
+compile-time guards select which checks are registered; a check is skipped if
 `mlk_sys_check_capability()` reports a required feature as unavailable.
 On unsupported architectures the registry is empty and the driver exits cleanly.
 
@@ -40,10 +41,8 @@ On unsupported architectures the registry is empty and the driver exits cleanly.
 
 Each kernel's buffer sizes, calling convention, and required CPU features come
 from a `/*yaml ... */` block in its `dev/` assembly source. `scripts/autogen`
-turns that into the per-kernel `check_<name>.c`, the `checks_<arch>_all.h`
-registry, and the per-arch `abicheck_<arch>.mk` (CFLAGS per feature, e.g.
-`-mavx2`), all included via `abicheck.mk` from `test/mk/components.mk`. Edit the
-YAML, not the generated files.
+turns that into the per-kernel `check_<name>.c` and the `checks_<arch>_all.h`
+registry. Edit the YAML, not the generated files.
 
 <!--- bibliography --->
 [^AAPCS32]: Arm Limited: Procedure Call Standard for the Arm Architecture (AAPCS32), [https://github.com/ARM-software/abi-aa/blob/main/aapcs32/aapcs32.rst](https://github.com/ARM-software/abi-aa/blob/main/aapcs32/aapcs32.rst)
diff --git a/test/abicheck/aarch64/abicheck_aarch64.mk b/test/abicheck/aarch64/abicheck_aarch64.mk
deleted file mode 100644
index 18404e5e91..0000000000
--- a/test/abicheck/aarch64/abicheck_aarch64.mk
+++ /dev/null
@@ -1,45 +0,0 @@
-# Copyright (c) The mlkem-native project authors
-# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
-
-# WARNING: This file is auto-generated from scripts/autogen
-#          in the mlkem-native repository.
-#          Do not modify it directly.
-#
-# Edit the YAML 'ABI.Features:' list in dev/<arch>/src/<kernel>.S
-# and re-run scripts/autogen instead.
-#
-# For each capability declared by a kernel's ABI.Features list, this
-# file appends the capability's CFLAGS to that kernel's .S object
-# under mlkem/src/.
-
-# Default each cap's file list to empty so the unconditional appends
-# below are safe even when a cap has no kernels on this arch.
-ABICHECK_REQ_NEON_FILES :=
-ABICHECK_REQ_SHA3_FILES :=
-
-# NEON: AArch64 NEON
-ABICHECK_REQ_NEON_FILES := \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_scalar_hybrid_aarch64_asm.S \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_intt_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_ntt_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_poly_mulcache_compute_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_poly_reduce_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_poly_tobytes_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_poly_tomont_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_aarch64_asm.S \
-  mlkem/src/native/aarch64/src/mlkem_rej_uniform_aarch64_asm.S
-ABICHECK_REQ_NEON_OBJS := $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_NEON_FILES))
-$(ABICHECK_REQ_NEON_OBJS): CFLAGS += -march=armv8-a+simd
-
-# SHA3: Armv8.4-A SHA3 (eor3, rax1, xar, bcax)
-ABICHECK_REQ_SHA3_FILES := \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x1_v84a_aarch64_asm.S \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x2_v84a_aarch64_asm.S \
-  mlkem/src/fips202/native/aarch64/src/keccak_f1600_x4_v8a_v84a_scalar_hybrid_aarch64_asm.S
-ABICHECK_REQ_SHA3_OBJS := $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_SHA3_FILES))
-$(ABICHECK_REQ_SHA3_OBJS): CFLAGS += -march=armv8.4-a+sha3
diff --git a/test/abicheck/aarch64/callstub_aarch64.S b/test/abicheck/aarch64/callstub_aarch64.S
index d3f8e81501..fa67994a97 100644
--- a/test/abicheck/aarch64/callstub_aarch64.S
+++ b/test/abicheck/aarch64/callstub_aarch64.S
@@ -5,6 +5,8 @@
 
 #include "../../../mlkem/src/sys.h"
 
+#if defined(MLK_SYS_AARCH64)
+
 #if defined(__ELF__)
 .section .note.GNU-stack,"",@progbits
 #endif
@@ -245,3 +247,5 @@ asm_call_stub_aarch64:
         .cfi_def_cfa_offset 0
         ret
         .cfi_endproc
+
+#endif /* MLK_SYS_AARCH64 */
diff --git a/test/abicheck/aarch64/selftest_aarch64.S b/test/abicheck/aarch64/selftest_aarch64.S
index 197fe67555..ef8c724fa7 100644
--- a/test/abicheck/aarch64/selftest_aarch64.S
+++ b/test/abicheck/aarch64/selftest_aarch64.S
@@ -5,6 +5,8 @@
 
 #include "../../../mlkem/src/sys.h"
 
+#if defined(MLK_SYS_AARCH64)
+
 /*
  * AArch64 selftest stubs.
  *
@@ -74,3 +76,5 @@ define_corrupter selftest_aarch64_corrupt_d13, "fneg d13, d13"
 define_corrupter selftest_aarch64_corrupt_d14, "fneg d14, d14"
 define_corrupter selftest_aarch64_corrupt_d15, "fneg d15, d15"
 #endif /* MLK_SYS_AARCH64_NEON */
+
+#endif /* MLK_SYS_AARCH64 */
diff --git a/test/abicheck/abicheck.mk b/test/abicheck/abicheck.mk
deleted file mode 100644
index 0204d07d52..0000000000
--- a/test/abicheck/abicheck.mk
+++ /dev/null
@@ -1,14 +0,0 @@
-# Copyright (c) The mlkem-native project authors
-# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
-
-# WARNING: This file is auto-generated from scripts/autogen
-#          in the mlkem-native repository.
-#          Do not modify it directly.
-#
-# Includes the per-arch abicheck_<arch>.mk, each of which appends
-# its capabilities' CFLAGS to the matching .S objects.
-
-include test/abicheck/aarch64/abicheck_aarch64.mk
-include test/abicheck/armv81m/abicheck_armv81m.mk
-include test/abicheck/ppc64le/abicheck_ppc64le.mk
-include test/abicheck/x86_64/abicheck_x86_64.mk
diff --git a/test/abicheck/armv81m/abicheck_armv81m.mk b/test/abicheck/armv81m/abicheck_armv81m.mk
deleted file mode 100644
index c6e8f058b4..0000000000
--- a/test/abicheck/armv81m/abicheck_armv81m.mk
+++ /dev/null
@@ -1,27 +0,0 @@
-# Copyright (c) The mlkem-native project authors
-# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
-
-# WARNING: This file is auto-generated from scripts/autogen
-#          in the mlkem-native repository.
-#          Do not modify it directly.
-#
-# Edit the YAML 'ABI.Features:' list in dev/<arch>/src/<kernel>.S
-# and re-run scripts/autogen instead.
-#
-# For each capability declared by a kernel's ABI.Features list, this
-# file appends the capability's CFLAGS to that kernel's .S object
-# under mlkem/src/.
-
-# Default each cap's file list to empty so the unconditional appends
-# below are safe even when a cap has no kernels on this arch.
-ABICHECK_REQ_MVE_FILES :=
-
-# MVE: Armv8.1-M MVE
-ABICHECK_REQ_MVE_FILES := \
-  mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_mve.S \
-  mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_extract_bytes_mve.S \
-  mlkem/src/fips202/native/armv81m/src/keccak_f1600_x4_state_xor_bytes_mve.S \
-  test/abicheck/armv81m/callstub_armv81m.S \
-  test/abicheck/armv81m/selftest_armv81m.S
-ABICHECK_REQ_MVE_OBJS := $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_MVE_FILES))
-$(ABICHECK_REQ_MVE_OBJS): CFLAGS += -march=armv8.1-m.main+mve -mthumb
diff --git a/test/abicheck/armv81m/callstub_armv81m.S b/test/abicheck/armv81m/callstub_armv81m.S
index 289edce8a9..6ae1267c55 100644
--- a/test/abicheck/armv81m/callstub_armv81m.S
+++ b/test/abicheck/armv81m/callstub_armv81m.S
@@ -3,6 +3,10 @@
  * SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
  */
 
+#include "../../../mlkem/src/sys.h"
+
+#if defined(MLK_SYS_ARMV81M_MVE)
+
 #if defined(__ELF__)
 .section .note.GNU-stack,"",%progbits
 #endif
@@ -181,3 +185,5 @@ asm_call_stub_armv81m:
         .cfi_adjust_cfa_offset -64
         pop     {r4-r12, pc}
         .cfi_endproc
+
+#endif /* MLK_SYS_ARMV81M_MVE */
diff --git a/test/abicheck/armv81m/checks/check_keccak_f1600_x4_mve_asm.c b/test/abicheck/armv81m/checks/check_keccak_f1600_x4_mve_asm.c
index 3f84d6186a..2913e4f1d8 100644
--- a/test/abicheck/armv81m/checks/check_keccak_f1600_x4_mve_asm.c
+++ b/test/abicheck/armv81m/checks/check_keccak_f1600_x4_mve_asm.c
@@ -14,7 +14,7 @@
 #include "../abicheck_armv81m.h"
 #include "../checks_armv81m_all.h"
 
-#if defined(MLK_SYS_ARMV81M_MVE) && defined(__ARM_FEATURE_MVE)
+#if defined(MLK_SYS_ARMV81M_MVE)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -76,4 +76,4 @@ int check_keccak_f1600_x4_mve_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_ARMV81M_MVE && __ARM_FEATURE_MVE */
+#endif /* MLK_SYS_ARMV81M_MVE */
diff --git a/test/abicheck/armv81m/checks_armv81m_all.h b/test/abicheck/armv81m/checks_armv81m_all.h
index 2f20ccaa71..2bb629310f 100644
--- a/test/abicheck/armv81m/checks_armv81m_all.h
+++ b/test/abicheck/armv81m/checks_armv81m_all.h
@@ -18,14 +18,10 @@
 
 #if defined(MLK_SYS_ARMV81M_MVE)
 
-#if defined(__ARM_FEATURE_MVE)
 int check_keccak_f1600_x4_mve_asm(void);
-#endif
 
 static const abicheck_entry_t all_checks[] = {
-#if defined(__ARM_FEATURE_MVE)
     {"keccak_f1600_x4_mve_asm", check_keccak_f1600_x4_mve_asm},
-#endif
     {NULL, NULL} /* Sentinel */
 };
 
diff --git a/test/abicheck/armv81m/selftest_armv81m.S b/test/abicheck/armv81m/selftest_armv81m.S
index e3f01c883e..8924706411 100644
--- a/test/abicheck/armv81m/selftest_armv81m.S
+++ b/test/abicheck/armv81m/selftest_armv81m.S
@@ -3,6 +3,10 @@
  * SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
  */
 
+#include "../../../mlkem/src/sys.h"
+
+#if defined(MLK_SYS_ARMV81M_MVE)
+
 /*
  * Armv8.1-M (Thumb-2, AAPCS32+MVE) selftest stubs.
  *
@@ -61,3 +65,5 @@ corrupt_q selftest_armv81m_corrupt_q4, q4
 corrupt_q selftest_armv81m_corrupt_q5, q5
 corrupt_q selftest_armv81m_corrupt_q6, q6
 corrupt_q selftest_armv81m_corrupt_q7, q7
+
+#endif /* MLK_SYS_ARMV81M_MVE */
diff --git a/test/abicheck/ppc64le/abicheck_ppc64le.mk b/test/abicheck/ppc64le/abicheck_ppc64le.mk
deleted file mode 100644
index acc89c0360..0000000000
--- a/test/abicheck/ppc64le/abicheck_ppc64le.mk
+++ /dev/null
@@ -1,28 +0,0 @@
-# Copyright (c) The mlkem-native project authors
-# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
-
-# WARNING: This file is auto-generated from scripts/autogen
-#          in the mlkem-native repository.
-#          Do not modify it directly.
-#
-# Edit the YAML 'ABI.Features:' list in dev/<arch>/src/<kernel>.S
-# and re-run scripts/autogen instead.
-#
-# For each capability declared by a kernel's ABI.Features list, this
-# file appends the capability's CFLAGS to that kernel's .S object
-# under mlkem/src/.
-
-# Default each cap's file list to empty so the unconditional appends
-# below are safe even when a cap has no kernels on this arch.
-ABICHECK_REQ_POWER8_VECTOR_FILES :=
-
-# POWER8_VECTOR: AltiVec/VSX and POWER8 vector extensions (Power ISA 2.07)
-ABICHECK_REQ_POWER8_VECTOR_FILES := \
-  mlkem/src/native/ppc64le/src/mlkem_intt_ppc_asm.S \
-  mlkem/src/native/ppc64le/src/mlkem_ntt_ppc_asm.S \
-  mlkem/src/native/ppc64le/src/mlkem_poly_tomont_ppc_asm.S \
-  mlkem/src/native/ppc64le/src/mlkem_reduce_ppc_asm.S \
-  test/abicheck/ppc64le/callstub_ppc64le.S \
-  test/abicheck/ppc64le/selftest_ppc64le.S
-ABICHECK_REQ_POWER8_VECTOR_OBJS := $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_POWER8_VECTOR_FILES))
-$(ABICHECK_REQ_POWER8_VECTOR_OBJS): CFLAGS += -mcpu=power8 -maltivec -mvsx
diff --git a/test/abicheck/x86_64/abicheck_x86_64.mk b/test/abicheck/x86_64/abicheck_x86_64.mk
deleted file mode 100644
index 638f4491d6..0000000000
--- a/test/abicheck/x86_64/abicheck_x86_64.mk
+++ /dev/null
@@ -1,43 +0,0 @@
-# Copyright (c) The mlkem-native project authors
-# SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
-
-# WARNING: This file is auto-generated from scripts/autogen
-#          in the mlkem-native repository.
-#          Do not modify it directly.
-#
-# Edit the YAML 'ABI.Features:' list in dev/<arch>/src/<kernel>.S
-# and re-run scripts/autogen instead.
-#
-# For each capability declared by a kernel's ABI.Features list, this
-# file appends the capability's CFLAGS to that kernel's .S object
-# under mlkem/src/.
-
-# Default each cap's file list to empty so the unconditional appends
-# below are safe even when a cap has no kernels on this arch.
-ABICHECK_REQ_AVX2_FILES :=
-
-# AVX2: AVX2
-ABICHECK_REQ_AVX2_FILES := \
-  mlkem/src/fips202/native/x86_64/src/keccak_f1600_x4_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_intt_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_ntt_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_nttfrombytes_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_ntttobytes_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_nttunpack_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_compress_d10_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_compress_d11_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_compress_d4_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_compress_d5_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_decompress_d10_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_decompress_d11_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_decompress_d4_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_decompress_d5_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_poly_mulcache_compute_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_reduce_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_rej_uniform_avx2_asm.S \
-  mlkem/src/native/x86_64/src/mlkem_tomont_avx2_asm.S
-ABICHECK_REQ_AVX2_OBJS := $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_REQ_AVX2_FILES))
-$(ABICHECK_REQ_AVX2_OBJS): CFLAGS += -mavx2 -mbmi2
diff --git a/test/abicheck/x86_64/callstub_x86_64.S b/test/abicheck/x86_64/callstub_x86_64.S
index eed080aaee..cacf77e188 100644
--- a/test/abicheck/x86_64/callstub_x86_64.S
+++ b/test/abicheck/x86_64/callstub_x86_64.S
@@ -3,6 +3,10 @@
  * SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
  */
 
+#include "../../../mlkem/src/sys.h"
+
+#if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED)
+
 /*
  * Function: asm_call_stub_x86_64_sysv
  * Description: x86_64 System V ABI compliance testing stub
@@ -147,3 +151,5 @@ asm_call_stub_x86_64_sysv:
         .cfi_restore %r15
         ret
         .cfi_endproc
+
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED */
diff --git a/test/abicheck/x86_64/checks/check_invntt_avx2_asm.c b/test/abicheck/x86_64/checks/check_invntt_avx2_asm.c
index a7c6a0ffbf..2314ce78f6 100644
--- a/test/abicheck/x86_64/checks/check_invntt_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_invntt_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -72,4 +72,4 @@ int check_invntt_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_keccak_f1600_x4_avx2_asm.c b/test/abicheck/x86_64/checks/check_keccak_f1600_x4_avx2_asm.c
index 33aa051e6d..3f8e3129a6 100644
--- a/test/abicheck/x86_64/checks/check_keccak_f1600_x4_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_keccak_f1600_x4_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -82,4 +82,4 @@ int check_keccak_f1600_x4_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_ntt_avx2_asm.c b/test/abicheck/x86_64/checks/check_ntt_avx2_asm.c
index b2185c6019..bbebcaa525 100644
--- a/test/abicheck/x86_64/checks/check_ntt_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_ntt_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -72,4 +72,4 @@ int check_ntt_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_nttfrombytes_avx2_asm.c b/test/abicheck/x86_64/checks/check_nttfrombytes_avx2_asm.c
index 90b9c29563..f9f16bd3f0 100644
--- a/test/abicheck/x86_64/checks/check_nttfrombytes_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_nttfrombytes_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -73,4 +73,4 @@ int check_nttfrombytes_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_ntttobytes_avx2_asm.c b/test/abicheck/x86_64/checks/check_ntttobytes_avx2_asm.c
index 36ad2af817..5cdc2f2ad3 100644
--- a/test/abicheck/x86_64/checks/check_ntttobytes_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_ntttobytes_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -74,4 +74,4 @@ int check_ntttobytes_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_nttunpack_avx2_asm.c b/test/abicheck/x86_64/checks/check_nttunpack_avx2_asm.c
index eaee811376..6a8e6a5643 100644
--- a/test/abicheck/x86_64/checks/check_nttunpack_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_nttunpack_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -70,4 +70,4 @@ int check_nttunpack_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_compress_d10_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_compress_d10_avx2_asm.c
index a30c040d04..063a3c89f8 100644
--- a/test/abicheck/x86_64/checks/check_poly_compress_d10_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_compress_d10_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_compress_d10_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_compress_d11_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_compress_d11_avx2_asm.c
index 8fc598be22..ba6453e070 100644
--- a/test/abicheck/x86_64/checks/check_poly_compress_d11_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_compress_d11_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_compress_d11_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_compress_d4_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_compress_d4_avx2_asm.c
index 5d819961be..74e290dfec 100644
--- a/test/abicheck/x86_64/checks/check_poly_compress_d4_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_compress_d4_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -77,4 +77,4 @@ int check_poly_compress_d4_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_compress_d5_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_compress_d5_avx2_asm.c
index e64c7966c2..2c852fa9cc 100644
--- a/test/abicheck/x86_64/checks/check_poly_compress_d5_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_compress_d5_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -77,4 +77,4 @@ int check_poly_compress_d5_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_decompress_d10_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_decompress_d10_avx2_asm.c
index c878ae7319..077fc33bc4 100644
--- a/test/abicheck/x86_64/checks/check_poly_decompress_d10_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_decompress_d10_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_decompress_d10_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_decompress_d11_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_decompress_d11_avx2_asm.c
index 573a11b47e..896b1c0a54 100644
--- a/test/abicheck/x86_64/checks/check_poly_decompress_d11_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_decompress_d11_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_decompress_d11_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_decompress_d4_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_decompress_d4_avx2_asm.c
index a27768ccf5..debbca9cfd 100644
--- a/test/abicheck/x86_64/checks/check_poly_decompress_d4_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_decompress_d4_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_decompress_d4_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_decompress_d5_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_decompress_d5_avx2_asm.c
index bdc2d6e806..b7c94995b8 100644
--- a/test/abicheck/x86_64/checks/check_poly_decompress_d5_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_decompress_d5_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_decompress_d5_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_poly_mulcache_compute_avx2_asm.c b/test/abicheck/x86_64/checks/check_poly_mulcache_compute_avx2_asm.c
index 1bacb3b763..32921dc402 100644
--- a/test/abicheck/x86_64/checks/check_poly_mulcache_compute_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_poly_mulcache_compute_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_poly_mulcache_compute_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.c b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.c
index 9e31b942c7..72d87683b3 100644
--- a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -82,4 +82,4 @@ int check_polyvec_basemul_acc_montgomery_cached_k2_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.c b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.c
index e1add85cbb..a7e58914d1 100644
--- a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -82,4 +82,4 @@ int check_polyvec_basemul_acc_montgomery_cached_k3_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.c b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.c
index 7cdabca54c..f4b17626a4 100644
--- a/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -82,4 +82,4 @@ int check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_reduce_avx2_asm.c b/test/abicheck/x86_64/checks/check_reduce_avx2_asm.c
index 9e1ed6bb67..586838503e 100644
--- a/test/abicheck/x86_64/checks/check_reduce_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_reduce_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -69,4 +69,4 @@ int check_reduce_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_rej_uniform_avx2_asm.c b/test/abicheck/x86_64/checks/check_rej_uniform_avx2_asm.c
index 3c65653861..2dcd60a715 100644
--- a/test/abicheck/x86_64/checks/check_rej_uniform_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_rej_uniform_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -78,4 +78,4 @@ int check_rej_uniform_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks/check_tomont_avx2_asm.c b/test/abicheck/x86_64/checks/check_tomont_avx2_asm.c
index 38db3122a2..ff4a6b3e91 100644
--- a/test/abicheck/x86_64/checks/check_tomont_avx2_asm.c
+++ b/test/abicheck/x86_64/checks/check_tomont_avx2_asm.c
@@ -15,7 +15,7 @@
 #include "../checks_x86_64_all.h"
 
 #if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED) && \
-    defined(__AVX2__)
+    defined(MLK_SYS_X86_64_AVX2)
 
 #include "../../../notrandombytes/notrandombytes.h"
 
@@ -69,4 +69,4 @@ int check_tomont_avx2_asm(void)
   return MLK_ABICHECK_PASSED;
 }
 
-#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && __AVX2__ */
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED && MLK_SYS_X86_64_AVX2 */
diff --git a/test/abicheck/x86_64/checks_x86_64_all.h b/test/abicheck/x86_64/checks_x86_64_all.h
index b7fbadaafc..aaaff96f81 100644
--- a/test/abicheck/x86_64/checks_x86_64_all.h
+++ b/test/abicheck/x86_64/checks_x86_64_all.h
@@ -19,7 +19,7 @@
 #if defined(MLK_SYS_X86_64)
 
 #if defined(MLK_SYSV_ABI_SUPPORTED)
-#if defined(__AVX2__)
+#if defined(MLK_SYS_X86_64_AVX2)
 int check_keccak_f1600_x4_avx2_asm(void);
 int check_invntt_avx2_asm(void);
 int check_ntt_avx2_asm(void);
@@ -41,12 +41,12 @@ int check_polyvec_basemul_acc_montgomery_cached_k4_avx2_asm(void);
 int check_reduce_avx2_asm(void);
 int check_rej_uniform_avx2_asm(void);
 int check_tomont_avx2_asm(void);
-#endif /* __AVX2__ */
+#endif /* MLK_SYS_X86_64_AVX2 */
 #endif /* MLK_SYSV_ABI_SUPPORTED */
 
 static const abicheck_entry_t all_checks[] = {
 #if defined(MLK_SYSV_ABI_SUPPORTED)
-#if defined(__AVX2__)
+#if defined(MLK_SYS_X86_64_AVX2)
     {"keccak_f1600_x4_avx2_asm", check_keccak_f1600_x4_avx2_asm},
     {"invntt_avx2_asm", check_invntt_avx2_asm},
     {"ntt_avx2_asm", check_ntt_avx2_asm},
@@ -71,7 +71,7 @@ static const abicheck_entry_t all_checks[] = {
     {"reduce_avx2_asm", check_reduce_avx2_asm},
     {"rej_uniform_avx2_asm", check_rej_uniform_avx2_asm},
     {"tomont_avx2_asm", check_tomont_avx2_asm},
-#endif           /* __AVX2__ */
+#endif           /* MLK_SYS_X86_64_AVX2 */
 #endif           /* MLK_SYSV_ABI_SUPPORTED */
     {NULL, NULL} /* Sentinel */
 };
diff --git a/test/abicheck/x86_64/selftest_x86_64.S b/test/abicheck/x86_64/selftest_x86_64.S
index a9f1af0604..e12a9ce63e 100644
--- a/test/abicheck/x86_64/selftest_x86_64.S
+++ b/test/abicheck/x86_64/selftest_x86_64.S
@@ -3,6 +3,10 @@
  * SPDX-License-Identifier: Apache-2.0 OR ISC OR MIT
  */
 
+#include "../../../mlkem/src/sys.h"
+
+#if defined(MLK_SYS_X86_64) && defined(MLK_SYSV_ABI_SUPPORTED)
+
 /*
  * x86_64 (System V) selftest stubs.
  *
@@ -39,3 +43,5 @@ define_corrupter selftest_x86_64_corrupt_r12, "notq %r12"
 define_corrupter selftest_x86_64_corrupt_r13, "notq %r13"
 define_corrupter selftest_x86_64_corrupt_r14, "notq %r14"
 define_corrupter selftest_x86_64_corrupt_r15, "notq %r15"
+
+#endif /* MLK_SYS_X86_64 && MLK_SYSV_ABI_SUPPORTED */
diff --git a/test/mk/components.mk b/test/mk/components.mk
index 3059580dc9..5c5363665c 100644
--- a/test/mk/components.mk
+++ b/test/mk/components.mk
@@ -198,20 +198,8 @@ else
 ABICHECK_ASM_SOURCES :=
 endif
 
-# Per-capability CFLAGS injection (e.g. -march=armv8.4-a+sha3 for SHA3,
-# -mavx2 -mbmi2 for AVX2), generated by scripts/autogen from each kernel's
-# YAML 'ABI.Features:' list. abicheck.mk includes the per-arch abicheck_<arch>.mk.
-include test/abicheck/abicheck.mk
-
-# SHA3-not-assemblable case: some aarch64 compilers do not support
-# `-march=armv8.4-a+sha3`, in which case we cannot even assemble the SHA3
-# Keccak kernels.
-ifeq ($(ARCH),aarch64)
-ifneq ($(MK_COMPILER_SUPPORTS_SHA3),1)
-ABICHECK_ASM_SOURCES := $(filter-out $(ABICHECK_REQ_SHA3_FILES),$(ABICHECK_ASM_SOURCES))
-endif
-endif
-
+# Compile the fixed source list with the platform's CPU flags. Each assembly
+# source uses the same system capability guards as the C checks.
 ABICHECK_ALL_SOURCES = $(ABICHECK_SOURCES) $(ABICHECK_ASM_SOURCES)
 ABICHECK_OBJS = $(call MAKE_OBJS,$(ABICHECK_DIR),$(ABICHECK_ALL_SOURCES))