diff --git a/tools/building.py b/tools/building.py
index 5ad6d4e9d2..38b7881797 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -267,6 +267,12 @@ def PrepareModuleBuilding(env, root_directory, bsp_directory):
     global Env
     global Rtt_Root
 
+    # patch for win32 spawn
+    if env['PLATFORM'] == 'win32':
+        win32_spawn = Win32Spawn()
+        win32_spawn.env = env
+        env['SPAWN'] = win32_spawn.spawn
+
     Env = env
     Rtt_Root = root_directory