diff --git a/tox.ini b/tox.ini
index 46f7f2d..6f5a8de 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,5 +12,6 @@ deps=
     py27,pypy: mock
 
 [testenv:flake8]
+basepython=python3
 deps=flake8
 commands=flake8