diff --git a/changelog.d/8688.misc b/changelog.d/8688.misc
new file mode 100644
index 0000000000..bef8dc425a
--- /dev/null
+++ b/changelog.d/8688.misc
@@ -0,0 +1 @@
+Abstract some invite-related code in preparation for landing knocking.
\ No newline at end of file
diff --git a/synapse/storage/databases/main/events_worker.py b/synapse/storage/databases/main/events_worker.py
index 5ae263827d..4732685f6e 100644
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -530,7 +530,7 @@ class EventsWorkerStore(SQLBaseStore):
         self,
         context: EventContext,
         state_types_to_include: List[EventTypes],
-        membership_user_id: Optional[str],
+        membership_user_id: Optional[str] = None,
     ) -> List[JsonDict]:
         """
         Retrieve the stripped state from a room, given an event context to retrieve state