1 files changed, 2 insertions, 3 deletions
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index 193959b250..ccd9f9d141 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -27,6 +27,7 @@ from typing import (
     Optional,
     Set,
     Tuple,
+    cast,
 )
 
 import attr
@@ -1348,9 +1349,7 @@ class PersistEventsStore:
             [event.event_id for event, _ in events_and_contexts],
         )
 
-        have_persisted: Dict[str, bool] = {
-            event_id: outlier for event_id, outlier in txn
-        }
+        have_persisted = dict(cast(Iterable[Tuple[str, bool]], txn))
 
         logger.debug(
             "_update_outliers_txn: events=%s have_persisted=%s",