1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 1536937b67..cb66376fb4 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -306,7 +306,7 @@ class PersistEventsStore:
 
         # The set of event_ids to return. This includes all soft-failed events
         # and their prev events.
-        existing_prevs = set()
+        existing_prevs: Set[str] = set()
 
         def _get_prevs_before_rejected_txn(
             txn: LoggingTransaction, batch: Collection[str]