diff --git a/tox.ini b/tox.ini
index ce451579ff..1b0133c5bf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,6 +27,7 @@ commands =
   nosetests test/unit/common/test_exceptions.py
 
 [testenv:pep8]
+basepython = python2.7
 commands =
   flake8 {posargs:swift test doc setup.py}
   flake8 --filename=swift* bin