diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index eacc0fb81fd..9b84894826a 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -1709,7 +1709,7 @@ async def _populate_participant(self, progress: JsonDict, batch_size: int) -> in
         """
         stream_token = progress.get("last_stream_token", None)
 
-        def _get_max_stream_token_txn(txn: LoggingTransaction) -> Optional[int]:
+        def _get_max_stream_token_txn(txn: LoggingTransaction) -> int:
             sql = """
                 SELECT event_stream_ordering from room_memberships
                 ORDER BY event_stream_ordering DESC
@@ -1717,7 +1717,7 @@ def _get_max_stream_token_txn(txn: LoggingTransaction) -> Optional[int]:
             """
             txn.execute(sql)
             res = txn.fetchone()
-            if not res[0]:
+            if not res or not res[0]:
                 return 0
             return res[0]