1 files changed, 9 insertions, 2 deletions
diff --git a/synapse/handlers/sliding_sync.py b/synapse/handlers/sliding_sync.py
index be98b379eb..1b5262d667 100644
--- a/synapse/handlers/sliding_sync.py
+++ b/synapse/handlers/sliding_sync.py
@@ -699,10 +699,17 @@ class SlidingSyncHandler:
                 instance_to_max_stream_ordering_map[instance_name] = stream_ordering
 
         # Then assemble the `RoomStreamToken`
+        min_stream_pos = min(instance_to_max_stream_ordering_map.values())
         membership_snapshot_token = RoomStreamToken(
             # Minimum position in the `instance_map`
-            stream=min(instance_to_max_stream_ordering_map.values()),
-            instance_map=immutabledict(instance_to_max_stream_ordering_map),
+            stream=min_stream_pos,
+            instance_map=immutabledict(
+                {
+                    instance_name: stream_pos
+                    for instance_name, stream_pos in instance_to_max_stream_ordering_map.items()
+                    if stream_pos > min_stream_pos
+                }
+            ),
         )
 
         # Since we fetched the users room list at some point in time after the from/to