diff --git a/tox.ini b/tox.ini
index 5863ec891..139a52320 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ ignore_basepython_conflict=true
 
 [testenv]
 basepython = python3
+usedevelop = True
 setenv =
   VIRTUAL_ENV={envdir}
   PYTHONDONTWRITEBYTECODE = 1