diff --git a/src/onebot/event/request/OB11BaseRequestEvent.ts b/src/onebot/event/request/OB11BaseRequestEvent.ts
index c8e9d145..efe69425 100644
--- a/src/onebot/event/request/OB11BaseRequestEvent.ts
+++ b/src/onebot/event/request/OB11BaseRequestEvent.ts
@@ -1,6 +1,6 @@
 import { EventType, OneBotEvent } from '@/onebot/event/OneBotEvent';
 
 export abstract class OB11BaseRequestEvent extends OneBotEvent {
-    post_type = EventType.REQUEST;
+    readonly post_type = EventType.REQUEST;
     abstract request_type: string;
 }