diff --git a/modoboa/lib/tests/__init__.py b/modoboa/lib/tests/__init__.py
index f5fa3172f..67245ef72 100644
--- a/modoboa/lib/tests/__init__.py
+++ b/modoboa/lib/tests/__init__.py
@@ -195,6 +195,8 @@ class SimpleModoTestCase(ParametersMixin, TestCase):
 class ModoTestCase(ParametersMixin, TestCase):
     """All test cases must inherit from this one."""
 
+    databases = "__all__"
+
     @classmethod
     def setUpTestData(cls):  # noqa
         """Create a default user."""
diff --git a/modoboa/policyd/tests.py b/modoboa/policyd/tests.py
index 9fc394a7f..aaf6cddf9 100644
--- a/modoboa/policyd/tests.py
+++ b/modoboa/policyd/tests.py
@@ -41,6 +41,8 @@ class PolicyDaemonTestCase(RedisTestCaseMixin, ParametersMixin, TransactionTestC
     A redis instance is required to run those tests.
     """
 
+    databases = "__all__"
+
     def setUp(self):
         super().setUp()
         call_command("load_initial_data")