diff --git a/docs/packages/pycolmap.yaml b/docs/packages/pycolmap.yaml
index f78eeafe512..1f382ec690d 100644
--- a/docs/packages/pycolmap.yaml
+++ b/docs/packages/pycolmap.yaml
@@ -34,3 +34,4 @@ versions:
   gpl-sources:
     filename: gpl-sources.tar
     description: gcc and the copyleft libraries bundled in the wheel
+- version: 4.2.1
diff --git a/patches/pycolmap/4.2.1/0001-build-drop-the-unused-clang-format-build-requirement.patch b/patches/pycolmap/4.2.1/0001-build-drop-the-unused-clang-format-build-requirement.patch
new file mode 100644
index 00000000000..b8e70817813
--- /dev/null
+++ b/patches/pycolmap/4.2.1/0001-build-drop-the-unused-clang-format-build-requirement.patch
@@ -0,0 +1,30 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Sun, 28 Sep 2026 00:00:00 +0000
+Subject: [PATCH] build: drop the unused clang-format build requirement
+
+Upstream-Status: Inappropriate [riscv64-only: clang-format 22.1.5 ships no riscv64 wheel, and the wheel build never runs it]
+
+clang-format is only used by scripts/format/c++.sh; neither
+python/CMakeLists.txt nor python/generate_stubs.sh (which formats the
+generated stubs with ruff) invokes it.  With no riscv64 wheel for the
+pinned 22.1.5, the isolated build environment would compile it from its
+sdist, i.e. a slice of LLVM, once per interpreter.
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ pyproject.toml | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/pyproject.toml b/pyproject.toml
+index e46baa57..976dd4e0 100644
+--- a/pyproject.toml
++++ b/pyproject.toml
+@@ -5,7 +5,6 @@ requires = [
+     "pybind11_stubgen @ git+https://github.com/sarlinpe/pybind11-stubgen@sarlinpe/fix-2025-08-20",
+     "numpy",
+     "ruff==0.15.20",
+-    "clang-format==22.1.5",
+ ]
+ build-backend = "scikit_build_core.build"
+