diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index d99fc4bec0..369b23a108 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -199,7 +199,8 @@ class InitialSyncHandler:
                     )
                 elif event.membership == Membership.LEAVE:
                     room_end_token = RoomStreamToken(
-                        stream=event.stream_ordering,
+                        stream=event.event_pos.stream,
+                        instance_map={event.event_pos: event.event_pos.stream},
                     )
                     deferred_room_state = run_in_background(
                         self._state_storage_controller.get_state_for_events,
diff --git a/synapse/handlers/sliding_sync.py b/synapse/handlers/sliding_sync.py
index 39009ef762..add7058389 100644
--- a/synapse/handlers/sliding_sync.py
+++ b/synapse/handlers/sliding_sync.py
@@ -323,7 +323,7 @@ class SlidingSyncHandler:
         room_for_user_list = await self.store.get_rooms_for_local_user_where_membership_is(
             user_id=user_id,
             # We want to fetch any kind of membership (joined and left rooms) in order
-            # to get the `stream_ordering` of the latest room membership event for the
+            # to get the `event_pos` of the latest room membership event for the
             # user.
             #
             # We will filter out the rooms that the user has left below (see
@@ -347,7 +347,7 @@ class SlidingSyncHandler:
         # Find the stream_ordering of the latest room membership event which will mark
         # the spot we queried up to.
         #
-        # TODO: With the new `GetRoomsForUserWithStreamOrdering` info, make a instance
+        # TODO: With the new `RoomsForUser.event_pos` info, make a instance
         # map to stream ordering and construct the new room key from that map,
         # `RoomStreamToken(stream=<min in that map>, instance_map=...)`
         max_stream_ordering_from_room_list = max(
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 9fddbb2caf..642cf96af8 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -476,7 +476,7 @@ class RoomMemberWorkerStore(EventsWorkerStore, CacheInvalidationWorkerStore):
         )
 
         sql = """
-            SELECT room_id, e.sender, c.membership, event_id, e.stream_ordering, r.room_version
+            SELECT room_id, e.sender, c.membership, event_id, e.instance_name, e.stream_ordering, r.room_version
             FROM local_current_membership AS c
             INNER JOIN events AS e USING (room_id, event_id)
             INNER JOIN rooms AS r USING (room_id)
@@ -488,7 +488,17 @@ class RoomMemberWorkerStore(EventsWorkerStore, CacheInvalidationWorkerStore):
         )
 
         txn.execute(sql, (user_id, *args))
-        results = [RoomsForUser(*r) for r in txn]
+        results = [
+            RoomsForUser(
+                room_id,
+                sender,
+                membership,
+                event_id,
+                PersistedEventPosition(instance_name, stream_ordering),
+                room_version,
+            )
+            for room_id, sender, membership, event_id, instance_name, stream_ordering, room_version in txn
+        ]
 
         return results
 
diff --git a/tests/replication/storage/test_events.py b/tests/replication/storage/test_events.py
index 86c8f14d1b..3df7fb89b5 100644
--- a/tests/replication/storage/test_events.py
+++ b/tests/replication/storage/test_events.py
@@ -154,7 +154,9 @@ class EventsWorkerStoreTestCase(BaseWorkerStoreTestCase):
                     USER_ID,
                     "invite",
                     event.event_id,
-                    event.internal_metadata.stream_ordering,
+                    PersistedEventPosition(
+                        "master", event.internal_metadata.stream_ordering
+                    ),
                     RoomVersions.V1.identifier,
                 )
             ],