diff --git a/matrix_appservice_kakaotalk/portal.py b/matrix_appservice_kakaotalk/portal.py
index b8d7370..0b6d6aa 100644
--- a/matrix_appservice_kakaotalk/portal.py
+++ b/matrix_appservice_kakaotalk/portal.py
@@ -1866,7 +1866,7 @@ class Portal(DBPortal, BasePortal):
             self.log.trace("Leaving room with %s post-backfill", intent.mxid)
             await intent.leave_room(self.mxid)
         self.log.info("Backfilled %d messages through %s", len(chats), source.mxid)
-        self._sync_read_receipts(source)
+        await self._sync_read_receipts(source)
 
     # region Database getters