From 4e9ab6a85f4a6120bd49163a9caae21e41b6a7f4 Mon Sep 17 00:00:00 2001
From: Markus Kowalewski <markus.kowalewski@gmail.com>
Date: Fri, 12 Sep 2025 23:20:26 +0200
Subject: [PATCH] mctc-lib: fix openmp cores in checkPhase

---
 pkgs/by-name/mc/mctc-lib/package.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/by-name/mc/mctc-lib/package.nix b/pkgs/by-name/mc/mctc-lib/package.nix
index 41a09bf7261e..6883ac8a7e6a 100644
--- a/pkgs/by-name/mc/mctc-lib/package.nix
+++ b/pkgs/by-name/mc/mctc-lib/package.nix
@@ -61,6 +61,10 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
+  preCheck = ''
+    export OMP_NUM_THREADS=2
+  '';
+
   postPatch = ''
     patchShebangs --build config/install-mod.py
   '';