diff --git a/tox.ini b/tox.ini
index 208aaa4aa..e798ee70f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -81,6 +81,7 @@ deps =
     w3lib==1.17.0
     zope.interface==4.1.3
     -rtests/requirements-py3.txt
+    mock
     # Extras
     botocore==1.3.23
     Pillow==3.4.2