diff --git a/tox.ini b/tox.ini
index 7c8010eb8..8a8204af2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,6 +30,7 @@ deps =
     pytest
     mock
     slimit
+    pillow
 whitelist_externals = py.test
 commands = {envpython} setup.py test