diff --git a/silverback/application.py b/silverback/application.py
index 272a3b53..7ea75fe0 100644
--- a/silverback/application.py
+++ b/silverback/application.py
@@ -261,7 +261,8 @@ def on_(
 
             if self.get_event_handler(container.contract.address, container.abi.name, input_filter):
                 raise DuplicateHandlerError(
-                    f"event {container.contract.address}:{container.abi.name}:{input_filter}"
+                    f"event {container.contract.address}:{container.abi.name}"
+                    f"({input_filter.filter_inputs if input_filter else ''})"
                 )
 
             key = container.contract.address