diff --git a/src/mra.py b/src/mra.py
index d5826bc6bc82d3dd17fc0e87f049c2a29f117dab..3e0229623f34f41cbf137719223f4a59f01379db 100644
--- a/src/mra.py
+++ b/src/mra.py
@@ -994,7 +994,7 @@ class MRA(object):
         # full_path = os.path.realpath(os.path.join(root, *args))
         full_path = os.path.join(root, *args)
         if not full_path.startswith(os.path.realpath(root)):
-            raise webapp.Forbidden(message="Path \"%s\" outside root directory." % (args))
+            raise webapp.Forbidden("Path \"%s\" outside root directory." % full_path)
         return full_path
 
     def mk_path(self, path):