diff --git a/src/backend/nio_callbacks.py b/src/backend/nio_callbacks.py
index d2808383..05d9d484 100644
--- a/src/backend/nio_callbacks.py
+++ b/src/backend/nio_callbacks.py
@@ -355,9 +355,11 @@ class NioCallbacks:
 
 
     async def onRoomMemberEvent(self, room, ev) -> None:
-        if ev.membership in ("invite", "join") and ev.state_key in room.users:
+        # The event can be a past event, don't trust it to update the model
+        # room's current state.
+        if ev.state_key in room.users:
             await self.client.add_member(room, user_id=ev.state_key)
-        elif ev.membership in ("left", "ban"):
+        else:
             await self.client.remove_member(room, user_id=ev.state_key)
 
         type_and_content = await self.process_room_member_event(room, ev)