1 files changed, 4 insertions, 1 deletions
diff --git a/synapse/storage/databases/state/bg_updates.py b/synapse/storage/databases/state/bg_updates.py
index 1fd333b707..75c09b3687 100644
--- a/synapse/storage/databases/state/bg_updates.py
+++ b/synapse/storage/databases/state/bg_updates.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import logging
+from typing import Optional
 
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.database import DatabasePool
@@ -73,8 +74,10 @@ class StateGroupBackgroundUpdateStore(SQLBaseStore):
             return count
 
     def _get_state_groups_from_groups_txn(
-        self, txn, groups, state_filter=StateFilter.all()
+        self, txn, groups, state_filter: Optional[StateFilter] = None
     ):
+        state_filter = state_filter or StateFilter.all()
+
         results = {group: {} for group in groups}
 
         where_clause, where_args = state_filter.make_sql_filter_clause()