diff --git a/astrbot/core/pipeline/waking_check/stage.py b/astrbot/core/pipeline/waking_check/stage.py
index e6716b37f..50599e818 100644
--- a/astrbot/core/pipeline/waking_check/stage.py
+++ b/astrbot/core/pipeline/waking_check/stage.py
@@ -81,7 +81,7 @@ class WakingCheckStage(Stage):
         if self.unique_session and event.message_obj.type == MessageType.GROUP_MESSAGE:
             sid = build_unique_session_id(event)
             if sid:
-                event.session.session_id = sid
+                event.session_id = sid
 
         # ignore bot self message
         if (