diff --git a/pyrogram/client/client.py b/pyrogram/client/client.py
index d6979c6d..81693d70 100644
--- a/pyrogram/client/client.py
+++ b/pyrogram/client/client.py
@@ -84,7 +84,7 @@ class Client:
         self.update_handler = None
 
     # TODO: Better update handler
-    def set_update_handler(self, callback):
+    def set_update_handler(self, callback: callable):
         self.update_handler = callback
 
     def send(self, data: Object):