diff --git a/haystack/components/joiners/list_joiner.py b/haystack/components/joiners/list_joiner.py
index 7d9d26579..ccd2e4fb8 100644
--- a/haystack/components/joiners/list_joiner.py
+++ b/haystack/components/joiners/list_joiner.py
@@ -77,7 +77,7 @@ class ListJoiner:
         if list_type_ is not None:
             component.set_output_types(self, values=list_type_)
         else:
-            component.set_output_types(self, values=List)
+            component.set_output_types(self, values=List[Any])
 
     def to_dict(self) -> Dict[str, Any]:
         """
diff --git a/test/components/joiners/test_list_joiner.py b/test/components/joiners/test_list_joiner.py
index 5d4f8849a..f5eb88b69 100644
--- a/test/components/joiners/test_list_joiner.py
+++ b/test/components/joiners/test_list_joiner.py
@@ -101,7 +101,8 @@ class TestListJoiner:
         pipe = Pipeline()
         pipe.add_component("joiner", joiner)
         pipe.add_component("llm", llm)
-        pipe.connect("joiner.values", "llm.messages")
+        with pytest.raises(PipelineConnectError):
+            pipe.connect("joiner.values", "llm.messages")
         assert pipe is not None
 
     def test_pipeline_connection_validation_list_chatmessage(self):