diff --git a/tox.ini b/tox.ini
index 687b5c2b..ba2d2668 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,6 +7,7 @@ commands =
 
 deps=
     pytest
+    greenlet
 
     lowest: Werkzeug==0.7
     lowest: Jinja2==2.4