diff --git a/VERSION b/VERSION
index 4b01aa8e..e13940b7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-Version 2.4.1-alpha.2+timestamp.2013.02.23.14.51.03
+Version 2.4.1-alpha.2+timestamp.2013.02.25.23.19.14
diff --git a/gluon/tools.py b/gluon/tools.py
index 3dd046e9..1cfc054a 100644
--- a/gluon/tools.py
+++ b/gluon/tools.py
@@ -3045,7 +3045,7 @@ class Auth(object):
         if not user_id and self.user:
             user_id = self.user.id
         membership = self.table_membership()
-        if self.db((membership.user_id == user_id)
+        if group_id and user_id and self.db((membership.user_id == user_id)
                     & (membership.group_id == group_id)).select():
             r = True
         else: