diff --git a/tox.ini b/tox.ini
index 53f0fb3..5e10486 100644
--- a/tox.ini
+++ b/tox.ini
@@ -50,7 +50,7 @@ deps:
 	passerelle: python-memcached
 	multitenant: systemd-python
 	https://git.entrouvert.org/debian/django-tenant-schemas.git/snapshot/django-tenant-schemas-master.tar.gz
-	mock
+	mock<4
 	httmock
 	requests
 	pytest-freezegun