diff --git a/tox.ini b/tox.ini
index af938446e9c8..071bf6e6a375 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,6 +24,7 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
 basepython = python2.7
+deps = hacking
 commands =
   bash tools/flake8wrap.sh {posargs}
   # Check that .po and .pot files are valid.