diff --git a/metagpt/roles/role.py b/metagpt/roles/role.py
index f74c32fea..356b9e33f 100644
--- a/metagpt/roles/role.py
+++ b/metagpt/roles/role.py
@@ -152,7 +152,7 @@ class Role(SerializationMixin, is_polymorphic_base=True):
     __hash__ = object.__hash__  # support Role as hashable type in `Environment.members`
 
     @model_validator(mode="after")
-    def check_subscription(self) -> set:
+    def check_subscription(self):
         if not self.subscription:
             self.subscription = {any_to_str(self), self.name} if self.name else {any_to_str(self)}
         return self
diff --git a/metagpt/utils/common.py b/metagpt/utils/common.py
index 5999b2e11..60acd7e3c 100644
--- a/metagpt/utils/common.py
+++ b/metagpt/utils/common.py
@@ -23,7 +23,7 @@ import sys
 import traceback
 import typing
 from pathlib import Path
-from typing import Any, Callable, List, Tuple, Union, get_args, get_origin
+from typing import Any, List, Tuple, Union, get_args, get_origin
 
 import aiofiles
 import loguru
@@ -365,14 +365,14 @@ def get_class_name(cls) -> str:
     return f"{cls.__module__}.{cls.__name__}"
 
 
-def any_to_str(val: str | Callable) -> str:
+def any_to_str(val: Any) -> str:
     """Return the class name or the class name of the object, or 'val' if it's a string type."""
     if isinstance(val, str):
         return val
-    if not callable(val):
+    elif not callable(val):
         return get_class_name(type(val))
-
-    return get_class_name(val)
+    else:
+        return get_class_name(val)
 
 
 def any_to_str_set(val) -> set: