diff --git a/tox.ini b/tox.ini
index 25418473..3e211be4 100644
--- a/tox.ini
+++ b/tox.ini
@@ -45,6 +45,7 @@ deps =
 [testenv:cov]
 deps =
     coverage
+    numpydoc
     {[testenv]deps}
 commands =
     coverage run --source jedi -m py.test