diff --git a/py/farm_ng/core/event_service.py b/py/farm_ng/core/event_service.py
index 0f9dba89..69c30a69 100644
--- a/py/farm_ng/core/event_service.py
+++ b/py/farm_ng/core/event_service.py
@@ -151,7 +151,7 @@ def request_reply_handler(self, handler: Callable) -> None:
 
     def add_request_reply_handler(self, handler: Callable) -> None:
         """Sets the request/reply handler."""
-        if not isinstance(handler, Callable):
+        if not type(handler) == Callable:
             msg = "handler must be a callable"
             raise TypeError(msg)