diff --git a/index.d.ts b/index.d.ts
index 0d1089c..c71bf76 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -167,6 +167,7 @@ declare namespace Pusher {
     event: string
     data: string
     socket_id: string
+    user_id?: string
   }
 
   interface WebHookData {