diff --git a/src/handlers.py b/src/handlers.py
index d7f11b4..0864641 100644
--- a/src/handlers.py
+++ b/src/handlers.py
@@ -51,7 +51,7 @@ _registry: dict[str, int] = {}
 _heartbeat: dict[str, float] = {}
 
 # UDP transport 引用，由 server.py 注入
-_udp_sender: callable | None = None
+_udp_sender: object | None = None
 
 
 def set_udp_sender(sender):