diff --git a/tox.ini b/tox.ini
index 5f65446e4..ad8835c46 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,9 +16,10 @@ deps=
 
 [testenv:py26]
 commands= py.test --lsof -rfsxX {posargs:testing}
+# pinning mock to last supported version for python 2.6
 deps=
     nose
-    mock<1.1  # last supported version for py26
+    mock<1.1
 
 [testenv:py27-subprocess]
 changedir=.