diff --git a/synapse/storage/databases/main/state.py b/synapse/storage/databases/main/state.py
index eba35f37000d..e6340f8285f4 100644
--- a/synapse/storage/databases/main/state.py
+++ b/synapse/storage/databases/main/state.py
@@ -396,6 +396,7 @@ def _update_state_for_partial_state_event_txn(
         )
 
         # TODO(faster_joins): need to do something about workers here
+        txn.call_after(self.is_partial_state_event.invalidate, (event.event_id,))
         txn.call_after(
             self._get_state_group_for_event.prefill,
             (event.event_id,),