diff --git a/tox.ini b/tox.ini
index df5d96bdf3..2b097a271a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -31,6 +31,7 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 
 [testenv:pep8]
+basepython = python2.7
 commands =
   bash tools/flake8wrap.sh {posargs}
   # Check that .po and .pot files are valid.