From e09e378ad0d91b656d5bcfa05da6d988aa26e5e4 Mon Sep 17 00:00:00 2001
From: OPNA2608 <opna2608@protonmail.com>
Date: Sat, 29 Nov 2025 14:31:21 +0100
Subject: [PATCH] python3Packages.scipy: Fix OMP_NUM_THREADS going 0

If NIX_BUILD_CORES < 4:

  libgomp: Invalid value for environment variable OMP_NUM_THREADS: 0
---
 pkgs/development/python-modules/scipy/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/development/python-modules/scipy/default.nix b/pkgs/development/python-modules/scipy/default.nix
index daa6cadf603f..e4c065629e46 100644
--- a/pkgs/development/python-modules/scipy/default.nix
+++ b/pkgs/development/python-modules/scipy/default.nix
@@ -193,6 +193,10 @@ buildPythonPackage (finalAttrs: {
 
   preCheck = ''
     export OMP_NUM_THREADS=$(( $NIX_BUILD_CORES / 4 ))
+    if [ $OMP_NUM_THREADS -eq 0 ]; then
+      export OMP_NUM_THREADS=1
+    fi
+
     cd $out
   '';