diff --git a/tests/api/test_evp_pkey.c b/tests/api/test_evp_pkey.c
index 632af9eae4d..51c8b5cef02 100644
--- a/tests/api/test_evp_pkey.c
+++ b/tests/api/test_evp_pkey.c
@@ -2440,6 +2440,12 @@ int test_wolfSSL_EVP_MD_ecc_signing(void)
                                           (unsigned int)XSTRLEN(testData)), 1);
     checkSz = sizeof(check);
     ExpectIntEQ(wolfSSL_EVP_DigestSignFinal(&mdCtx, NULL, &checkSz), 1);
+    ExpectIntEQ((int)checkSz, wolfSSL_EVP_PKEY_size(privKey));
+    /* A buffer too small for the signature is an error. */
+    checkSz = 8;
+    ExpectIntEQ(wolfSSL_EVP_DigestSignFinal(&mdCtx, check, &checkSz), 0);
+    ExpectIntEQ((int)checkSz, 8);
+    ExpectIntEQ(check[0], 0);
     checkSz = sizeof(check);
     ExpectIntEQ(wolfSSL_EVP_DigestSignFinal(&mdCtx, check, &checkSz), 1);
     ret = wolfSSL_EVP_MD_CTX_cleanup(&mdCtx);
@@ -2487,6 +2493,43 @@ int test_wolfSSL_EVP_MD_ecc_signing(void)
     return EXPECT_RESULT();
 }
 
+int test_wolfSSL_EVP_DigestSignFinal_ecc_size(void)
+{
+    EXPECT_DECLS;
+#if defined(OPENSSL_EXTRA) && defined(HAVE_ECC) && !defined(NO_SHA256) && \
+    defined(HAVE_ECC_BRAINPOOL) && \
+    (defined(HAVE_ECC512) || defined(HAVE_ALL_CURVES)) && \
+    ECC_MIN_KEY_SZ <= 512 && FIPS_VERSION3_LT(6,0,0)
+    WOLFSSL_EC_KEY* ecKey = NULL;
+    WOLFSSL_EVP_PKEY* pkey = NULL;
+    WOLFSSL_EVP_MD_CTX mdCtx;
+    size_t sigSz = 0;
+    int ret;
+
+    ExpectNotNull(ecKey = wolfSSL_EC_KEY_new_by_curve_name(
+        NID_brainpoolP512r1));
+    ExpectIntEQ(wolfSSL_EC_KEY_generate_key(ecKey), 1);
+    ExpectNotNull(pkey = wolfSSL_EVP_PKEY_new());
+    ExpectIntEQ(wolfSSL_EVP_PKEY_assign_EC_KEY(pkey, ecKey), WOLFSSL_SUCCESS);
+    if (EXPECT_FAIL()) {
+        wolfSSL_EC_KEY_free(ecKey);
+    }
+
+    wolfSSL_EVP_MD_CTX_init(&mdCtx);
+    ExpectIntEQ(wolfSSL_EVP_DigestSignInit(&mdCtx, NULL, wolfSSL_EVP_sha256(),
+        NULL, pkey), 1);
+    ExpectIntEQ(wolfSSL_EVP_DigestSignFinal(&mdCtx, NULL, &sigSz), 1);
+    /* r and s may need a leading zero and the SEQ length is two bytes. */
+    ExpectIntEQ((int)sigSz, 137);
+    ExpectIntEQ((int)sigSz, wolfSSL_EVP_PKEY_size(pkey));
+    ret = wolfSSL_EVP_MD_CTX_cleanup(&mdCtx);
+    ExpectIntEQ(ret, 1);
+
+    wolfSSL_EVP_PKEY_free(pkey);
+#endif
+    return EXPECT_RESULT();
+}
+
 
 int test_wolfSSL_EVP_DigestSign(void)
 {
diff --git a/tests/api/test_evp_pkey.h b/tests/api/test_evp_pkey.h
index 874391edb21..1db3107f3b6 100644
--- a/tests/api/test_evp_pkey.h
+++ b/tests/api/test_evp_pkey.h
@@ -65,6 +65,7 @@ int test_wolfSSL_EVP_PKEY_verify_dsa_len(void);
 int test_wolfSSL_EVP_MD_rsa_signing(void);
 int test_wc_RsaPSS_DigitalSignVerify(void);
 int test_wolfSSL_EVP_MD_ecc_signing(void);
+int test_wolfSSL_EVP_DigestSignFinal_ecc_size(void);
 int test_wolfSSL_EVP_DigestSign(void);
 int test_wolfSSL_EVP_DigestSign_ecc(void);
 int test_wolfSSL_EVP_PKEY_encrypt(void);
@@ -126,6 +127,7 @@ int test_wolfSSL_CTX_use_PrivateKey_pkcs8_repopulate(void);
     TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_MD_rsa_signing),              \
     TEST_DECL_GROUP("evp_pkey", test_wc_RsaPSS_DigitalSignVerify),             \
     TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_MD_ecc_signing),              \
+    TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_DigestSignFinal_ecc_size),    \
     TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_DigestSign),                  \
     TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_DigestSign_ecc),              \
     TEST_DECL_GROUP("evp_pkey", test_wolfSSL_EVP_PKEY_encrypt),                \
diff --git a/wolfcrypt/src/evp.c b/wolfcrypt/src/evp.c
index 3b212155b64..6164dff91f2 100644
--- a/wolfcrypt/src/evp.c
+++ b/wolfcrypt/src/evp.c
@@ -5225,9 +5225,17 @@ int wolfSSL_EVP_DigestSignFinal(WOLFSSL_EVP_MD_CTX *ctx, unsigned char *sig,
 #ifdef HAVE_ECC
     else if (ctx->pctx->pkey->type == WC_EVP_PKEY_EC) {
         if (sig == NULL) {
-            /* SEQ + INT + INT */
-            *siglen = (size_t)ecc_sets[ctx->pctx->pkey->ecc->group->curve_idx].
-                size * 2 + 8;
+            WOLFSSL_EC_KEY* key = ctx->pctx->pkey->ecc;
+            int sigSz;
+
+            if (key == NULL || (key->inSet == 0 &&
+                    SetECKeyInternal(key) != WOLFSSL_SUCCESS)) {
+                return WOLFSSL_FAILURE;
+            }
+            sigSz = wc_ecc_sig_size((ecc_key*)key->internal);
+            if (sigSz <= 0)
+                return WOLFSSL_FAILURE;
+            *siglen = (size_t)sigSz;
             return WOLFSSL_SUCCESS;
         }
     }
@@ -5277,8 +5285,10 @@ int wolfSSL_EVP_DigestSignFinal(WOLFSSL_EVP_MD_CTX *ctx, unsigned char *sig,
             len = wolfSSL_i2d_ECDSA_SIG(ecdsaSig, NULL);
             if (len > 0 && (size_t)len <= *siglen)
                 len = wolfSSL_i2d_ECDSA_SIG(ecdsaSig, &sig);
+            else
+                len = 0;
             wolfSSL_ECDSA_SIG_free(ecdsaSig);
-            if (len == 0)
+            if (len <= 0)
                 break;
             *siglen = (size_t)len;
             ret = WOLFSSL_SUCCESS;