diff --git a/tests/unittest.py b/tests/unittest.py

index a1bdd963e6..b30b7d1718 100644
--- a/tests/unittest.py
+++ b/tests/unittest.py
@@ -402,10 +402,12 @@ class HomeserverTestCase(TestCase):
         hs = setup_test_homeserver(self.addCleanup, *args, **kwargs)
         stor = hs.get_datastore()
 
-        # Run the database background updates.
-        if hasattr(stor, "do_next_background_update"):
-            while not self.get_success(stor.has_completed_background_updates()):
-                self.get_success(stor.do_next_background_update(1))
+        # Run the database background updates, when running against "master".
+        if hs.__class__.__name__ == "TestHomeServer":
+            while not self.get_success(
+                stor.db.updates.has_completed_background_updates()
+            ):
+                self.get_success(stor.db.updates.do_next_background_update(1))
 
         return hs
 
@@ -549,7 +551,7 @@ class HomeserverTestCase(TestCase):
         Add the given event as an extremity to the room.
         """
         self.get_success(
-            self.hs.get_datastore().simple_insert(
+            self.hs.get_datastore().db.simple_insert(
                 table="event_forward_extremities",
                 values={"room_id": room_id, "event_id": event_id},
                 desc="test_add_extremity",