diff --git a/synapse/storage/data_stores/main/events_bg_updates.py b/synapse/storage/data_stores/main/events_bg_updates.py
index e702fca149..013242b04e 100644
--- a/synapse/storage/data_stores/main/events_bg_updates.py
+++ b/synapse/storage/data_stores/main/events_bg_updates.py
@@ -524,7 +524,7 @@ class EventsBackgroundUpdatesStore(BackgroundUpdateStore):
                 (last_event_id, batch_size)
             )
 
-            rows = txn.fetchall()
+            rows = self.cursor_to_dict(txn)
             if not rows:
                 return True