diff --git a/src/pydantype/utils.py b/src/pydantype/utils.py
index 5717863..bd78c9a 100644
--- a/src/pydantype/utils.py
+++ b/src/pydantype/utils.py
@@ -1,8 +1,8 @@
 from typing import Any, Union, get_origin, get_args
 from pydantic import BaseModel
 
-def is_pydantic_model(obj: Any) -> bool:
-    return isinstance(obj, type) and issubclass(obj, BaseModel)
+def is_pydantic_model(type_: type) -> bool:
+    return isinstance(type_, type) and not isinstance(type_, GenericAlias) and (issubclass(type_, BaseModel))
 
 def is_optional(annotation: Any) -> bool:
-    return get_origin(annotation) is Union and type(None) in get_args(annotation)
\ No newline at end of file
+    return get_origin(annotation) is Union and type(None) in get_args(annotation)