diff --git a/tools/building.py b/tools/building.py
index 3c2dbc4e74..83f034deb3 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -493,6 +493,9 @@ def EndBuilding(target, program = None):
         CscopeDatabase(Projects)
 
 def SrcRemove(src, remove):
+    if not src:
+        return
+
     if type(src[0]) == type('str'):
         for item in src:
             if os.path.basename(item) in remove: