diff --git a/product/ERP5Type/Tool/ClassTool.py b/product/ERP5Type/Tool/ClassTool.py
index 42608cd720d005297891f0a7ec62a134f7a619b0..0bbbc702e6e856e0af7d7647fdea6df30d23a265 100644
--- a/product/ERP5Type/Tool/ClassTool.py
+++ b/product/ERP5Type/Tool/ClassTool.py
@@ -1203,7 +1203,7 @@ def initialize( context ):
         return result
 
       security.declareProtected(Permissions.ManagePortal, 'runLiveTest')
-      def runLiveTest(self, test_list=None, run_only=None, debug=None,
+      def runLiveTest(self, test_list=None, run_only=None, debug=False,
                       verbose=False):
         """
         Launch live tests