diff --git a/tox.ini b/tox.ini
index 87e49ef..a2ffedc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py26,py27,pep8
+envlist = py26,py27,py33,pep8
 
 [testenv]
 setenv =