diff --git a/tox.ini b/tox.ini
index 6d7beb1..16b3642 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,7 +3,7 @@ envlist = py26,py27,py33,py34,pypy,cover
 
 [testenv]
 basedeps = keyring
-           mock
+           mock==1.0.1
            pycrypto==2.6
            webtest
            nose