diff --git a/asyncua/client/client.py b/asyncua/client/client.py
index 3e7ccb750..e8cf1d664 100644
--- a/asyncua/client/client.py
+++ b/asyncua/client/client.py
@@ -72,7 +72,7 @@ def __init__(self, url: str, timeout: float = 4, watchdog_intervall: float = 1.0
         self.secure_channel_id = None
         self.secure_channel_timeout = 3600000  # 1 hour
         self.session_timeout = 3600000  # 1 hour
-        self.connection_lost_callback: Optional[Callable[[Exception], None]] = None
+        self.connection_lost_callback: Optional[Callable[[Exception], Coroutine[Any, Any, None]]] = None
         self._policy_ids: List[ua.UserTokenPolicy] = []
         self.uaclient: UaClient = UaClient(timeout)
         self.uaclient.pre_request_hook = self.check_connection
@@ -561,7 +561,7 @@ async def _monitor_server_loop(self):
             await self.uaclient.inform_subscriptions(ua.StatusCode(ua.StatusCodes.BadShutdown))
             raise
 
-    async def _lost_connection(self, ex: BaseException):
+    async def _lost_connection(self, ex: Exception):
         if not self.connection_lost_callback:
             return
         try: