diff --git a/tox.ini b/tox.ini
index 9f2be3ff2..a8a72b46f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -47,6 +47,7 @@ deps =
     dj22: Django>=2.2,<2.3
     dj22stable: git+https://github.com/django/django.git@stable/2.2.x#egg=Django
     djmaster: git+https://github.com/django/django.git@master#egg=Django
+    djmaster: git+https://github.com/wagtail/django-modelcluster.git
 
     postgres: psycopg2>=2.6
     mysql: mysqlclient>=1.3.7,<1.4