diff --git a/lib/rapi/rlib2.py b/lib/rapi/rlib2.py
index 5d65ce2d1e9db193eaeacf975b121f4b17b55906..790839a700398c7818820284795b1bfa156b3c8d 100644
--- a/lib/rapi/rlib2.py
+++ b/lib/rapi/rlib2.py
@@ -233,7 +233,7 @@ class R_2_instances_name_tags(baserlib.R_Generic):
     """
     if 'tag' not in self.queryargs:
       # no we not gonna delete all tags from an instance
-      raise http.HTTPNotImplemented
+      raise http.HTTPNotImplemented()
     return baserlib._Tags_DELETE(constants.TAG_INSTANCE,
                                  self.queryargs['tag'],
                                  name=self.items[0])