diff --git a/tools/building.py b/tools/building.py
index 0b361dde28..d95cf3672f 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -259,6 +259,7 @@ def PrepareBuilding(env, root_directory, has_libcpu=False, remove_components = [
 def PrepareModuleBuilding(env, root_directory, bsp_directory):
     import rtconfig
 
+    global BuildOptions
     global Env
     global Rtt_Root