diff --git a/tox.ini b/tox.ini
index 176c6e0ab..3e8688c6b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -35,6 +35,7 @@ deps =
     pyopenssl
     pyxdg
     pytest
+    pytest-twisted
     mock
     slimit
     pillow