1 files changed, 3 insertions, 2 deletions
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index c42dac18f5..9a86eb01c9 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -31,6 +31,7 @@ from synapse.storage.state import StateFilter
 from synapse.types import (
     Collection,
     JsonDict,
+    MutableStateMap,
     RoomStreamToken,
     StateMap,
     StreamToken,
@@ -588,7 +589,7 @@ class SyncHandler(object):
         room_id: str,
         sync_config: SyncConfig,
         batch: TimelineBatch,
-        state: StateMap[EventBase],
+        state: MutableStateMap[EventBase],
         now_token: StreamToken,
     ) -> Optional[JsonDict]:
         """ Works out a room summary block for this room, summarising the number
@@ -736,7 +737,7 @@ class SyncHandler(object):
         since_token: Optional[StreamToken],
         now_token: StreamToken,
         full_state: bool,
-    ) -> StateMap[EventBase]:
+    ) -> MutableStateMap[EventBase]:
         """ Works out the difference in state between the start of the timeline
         and the previous sync.