diff --git a/py/_test/session.py b/py/_test/session.py
index 47e93e5d2..66ea640ab 100644
--- a/py/_test/session.py
+++ b/py/_test/session.py
@@ -22,6 +22,7 @@ class Session(object):
     nodeid = ""
     class Interrupted(KeyboardInterrupt):
         """ signals an interrupted test run. """
+        __module__ = 'builtins' # for py3
         
     def __init__(self, config):
         self.config = config