From bf051c4b0202311ee8edf30cdebc7e9399078e73 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Sch=C3=BCtz?= <nix@dotlambda.de>
Date: Tue, 10 Feb 2026 10:07:33 -0800
Subject: [PATCH] python3Packages.grpcio-tools: fix build

---
 .../python-modules/grpcio-tools/default.nix           | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/python-modules/grpcio-tools/default.nix b/pkgs/development/python-modules/grpcio-tools/default.nix
index 552d257d8085..00033efa4620 100644
--- a/pkgs/development/python-modules/grpcio-tools/default.nix
+++ b/pkgs/development/python-modules/grpcio-tools/default.nix
@@ -3,6 +3,7 @@
   buildPythonPackage,
   fetchPypi,
   protobuf,
+  cython,
   grpcio,
   setuptools,
 }:
@@ -21,6 +22,11 @@ buildPythonPackage rec {
     hash = "sha256-Sw3YZWAnQxbhVdklFYJ2+FZFCBkwiLxD4g0/Xf+Vays=";
   };
 
+  postPatch = ''
+    substituteInPlace pyproject.toml \
+      --replace-fail "Cython==3.1.1" Cython
+  '';
+
   outputs = [
     "out"
     "dev"
@@ -28,7 +34,10 @@ buildPythonPackage rec {
 
   enableParallelBuilding = true;
 
-  build-system = [ setuptools ];
+  build-system = [
+    cython
+    setuptools
+  ];
 
   pythonRelaxDeps = [
     "protobuf"