diff --git a/tox.ini b/tox.ini
index 62e12f990..5cb4cb8c4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,6 +13,8 @@ extras =
     pytz20187: pytz==2018.7
     pytz_latest: pytz
 
+commands_pre =
+    pip install -e '.[test]'
 commands =
     py.test {posargs}