diff --git a/pytypes/type_util.py b/pytypes/type_util.py
index 13c991e..f6227c8 100644
--- a/pytypes/type_util.py
+++ b/pytypes/type_util.py
@@ -900,7 +900,7 @@ def resolve_fw_decl(in_type, module_name=None, globs=None, level=0):
                 for in_tp in args])
         ret = resolve_fw_decl(res, None, globs)[1] or ret
         return in_type, ret
-    elif hasattr(in_type, '__args__'):
+    elif hasattr(in_type, '__args__') and in_type.__args__ is not None:
         return in_type, any([resolve_fw_decl(in_tp, None, globs)[1] \
                 for in_tp in in_type.__args__])
     return in_type, False

NoneType' object is not iterable in resolve_fw_decl
```python
>>> import typing
>>> from pytypes import type_util
>>> T = typing.TypeVar('T')
>>> class Foo(typing.Generic[T]):
...   pass
... 
>>> type_util.resolve_fw_decl(Foo)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not iterable
```
diff --git a/tests/test_typechecker.py b/tests/test_typechecker.py
index d6acaf9..ddd2745 100644
--- a/tests/test_typechecker.py
+++ b/tests/test_typechecker.py
@@ -23,7 +23,7 @@ from numbers import Real
 import pytypes
 from pytypes import typechecked, override, auto_override, no_type_check, get_types, \
     get_type_hints, TypeCheckError, InputTypeError, ReturnTypeError, OverrideError, \
-    TypeSyntaxError, check_argument_types, annotations, get_member_types
+    TypeSyntaxError, check_argument_types, annotations, get_member_types, resolve_fw_decl
 pytypes.clean_traceback = False
 try:
     from backports import typing
@@ -4652,5 +4652,18 @@ class Test_check_argument_types_Python3_5(unittest.TestCase):
         self.assertRaises(InputTypeError, lambda:
                 py3.test_inner_class_testf1_err())
 
+
+class Test_utils(unittest.TestCase):
+    # See: https://github.com/Stewori/pytypes/issues/36
+    def test_resolve_fw_decl(self):
+        T = typing.TypeVar('T')
+
+        class Foo(typing.Generic[T]):
+            pass
+
+        # No exception.
+        resolve_fw_decl(Foo)
+
+
 if __name__ == '__main__':
     unittest.main()

pip install -e .[dev]
parse_log_pytest
pytest
pytest
3.6
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs @ file:///opt/conda/conda-bld/attrs_1642510447205/work
certifi==2021.5.30
importlib-metadata @ file:///tmp/build/80754af9/importlib-metadata_1631916693255/work
iniconfig @ file:///home/linux1/recipes/ci/iniconfig_1610983019677/work
more-itertools @ file:///tmp/build/80754af9/more-itertools_1637733554872/work
packaging @ file:///tmp/build/80754af9/packaging_1637314298585/work
pluggy @ file:///tmp/build/80754af9/pluggy_1615976315926/work
py @ file:///opt/conda/conda-bld/py_1644396412707/work
pyparsing @ file:///tmp/build/80754af9/pyparsing_1635766073266/work
pytest==6.2.4
-e git+https://github.com/Stewori/pytypes.git@5736ecd2878aca5c78df44aeeaef13303cbfa5f2#egg=pytypes
toml @ file:///tmp/build/80754af9/toml_1616166611790/work
typing_extensions @ file:///opt/conda/conda-bld/typing_extensions_1647553014482/work
zipp @ file:///tmp/build/80754af9/zipp_1633618647012/work

name: pytypes
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - attrs=21.4.0=pyhd3eb1b0_0
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - importlib-metadata=4.8.1=py36h06a4308_0
  - importlib_metadata=4.8.1=hd3eb1b0_0
  - iniconfig=1.1.1=pyhd3eb1b0_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - more-itertools=8.12.0=pyhd3eb1b0_0
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - packaging=21.3=pyhd3eb1b0_0
  - pip=21.2.2=py36h06a4308_0
  - pluggy=0.13.1=py36h06a4308_0
  - py=1.11.0=pyhd3eb1b0_0
  - pyparsing=3.0.4=pyhd3eb1b0_0
  - pytest=6.2.4=py36h06a4308_2
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - toml=0.10.2=pyhd3eb1b0_0
  - typing_extensions=4.1.1=pyh06a4308_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zipp=3.6.0=pyhd3eb1b0_0
  - zlib=1.2.13=h5eee18b_1
prefix: /opt/conda/envs/pytypes

tests/test_typechecker.py::Test_utils::test_resolve_fw_decl
tests/test_typechecker.py::testfunc tests/test_typechecker.py::testfunc_err tests/test_typechecker.py::testfunc2 tests/test_typechecker.py::testfunc4 tests/test_typechecker.py::testfunc_None_ret tests/test_typechecker.py::testfunc_None_ret_err tests/test_typechecker.py::testfunc_None_arg tests/test_typechecker.py::testfunc_Dict_arg tests/test_typechecker.py::testfunc_Mapping_arg tests/test_typechecker.py::testfunc_Dict_ret tests/test_typechecker.py::testfunc_Dict_ret_err tests/test_typechecker.py::testfunc_Seq_arg tests/test_typechecker.py::testfunc_Seq_ret_List tests/test_typechecker.py::testfunc_Seq_ret_Tuple tests/test_typechecker.py::testfunc_Seq_ret_err tests/test_typechecker.py::testfunc_Iter_arg tests/test_typechecker.py::testfunc_Iter_str_arg tests/test_typechecker.py::testfunc_Iter_ret_err tests/test_typechecker.py::testfunc_Callable_arg tests/test_typechecker.py::testfunc_Callable_call_err tests/test_typechecker.py::testfunc_Callable_ret tests/test_typechecker.py::testfunc_Callable_ret_err tests/test_typechecker.py::testfunc_Generator_arg tests/test_typechecker.py::testfunc_Generator_ret tests/test_typechecker.py::testfunc_Generic_arg tests/test_typechecker.py::testfunc_Generic_ret tests/test_typechecker.py::testfunc_Generic_ret_err tests/test_typechecker.py::testfunc_numeric_tower_float tests/test_typechecker.py::testfunc_numeric_tower_complex tests/test_typechecker.py::testfunc_numeric_tower_tuple tests/test_typechecker.py::testfunc_numeric_tower_return tests/test_typechecker.py::testfunc_numeric_tower_return_err tests/test_typechecker.py::testfunc_custom_annotations_typechecked tests/test_typechecker.py::testfunc_custom_annotations_typechecked_err tests/test_typechecker.py::testfunc_varargs2 tests/test_typechecker.py::testfunc_varargs3 tests/test_typechecker.py::testfunc_varargs5 tests/test_typechecker.py::testfunc_varargs_err tests/test_typechecker.py::testfunc_varargs_ca3
tests/test_typechecker.py::testfunc_Iter_ret tests/test_typechecker.py::testfunc_Generator tests/test_typechecker.py::testfunc_varargs1 tests/test_typechecker.py::testfunc_varargs4 tests/test_typechecker.py::testClass2_defTimeCheck tests/test_typechecker.py::testClass2_defTimeCheck2 tests/test_typechecker.py::testClass2_defTimeCheck3 tests/test_typechecker.py::testClass2_defTimeCheck4 tests/test_typechecker.py::testClass3_defTimeCheck tests/test_typechecker.py::testClass2_defTimeCheck_init_ov tests/test_typechecker.py::testfunc_check_argument_types_empty tests/test_typechecker.py::testfunc_varargs_ca1 tests/test_typechecker.py::testfunc_varargs_ca4 tests/test_typechecker.py::TestTypecheck::test_abstract_override tests/test_typechecker.py::TestTypecheck::test_annotations_from_typestring tests/test_typechecker.py::TestTypecheck::test_callable tests/test_typechecker.py::TestTypecheck::test_classmethod tests/test_typechecker.py::TestTypecheck::test_custom_annotations tests/test_typechecker.py::TestTypecheck::test_custom_generic tests/test_typechecker.py::TestTypecheck::test_defaults_inferred_types tests/test_typechecker.py::TestTypecheck::test_dict tests/test_typechecker.py::TestTypecheck::test_empty tests/test_typechecker.py::TestTypecheck::test_function tests/test_typechecker.py::TestTypecheck::test_generator tests/test_typechecker.py::TestTypecheck::test_get_generic_parameters tests/test_typechecker.py::TestTypecheck::test_get_types tests/test_typechecker.py::TestTypecheck::test_iterable tests/test_typechecker.py::TestTypecheck::test_method tests/test_typechecker.py::TestTypecheck::test_method_forward tests/test_typechecker.py::TestTypecheck::test_numeric_tower tests/test_typechecker.py::TestTypecheck::test_parent_typecheck_no_override tests/test_typechecker.py::TestTypecheck::test_parent_typecheck_other_signature tests/test_typechecker.py::TestTypecheck::test_property tests/test_typechecker.py::TestTypecheck::test_sequence tests/test_typechecker.py::TestTypecheck::test_staticmethod tests/test_typechecker.py::TestTypecheck::test_subtype_class_extends_generic tests/test_typechecker.py::TestTypecheck::test_typecheck_parent_type tests/test_typechecker.py::TestTypecheck::test_typestring_varargs_syntax tests/test_typechecker.py::TestTypecheck::test_typevar_class tests/test_typechecker.py::TestTypecheck::test_typevar_func tests/test_typechecker.py::TestTypecheck::test_unparameterized tests/test_typechecker.py::TestTypecheck::test_varargs tests/test_typechecker.py::TestTypecheck::test_varargs_check_argument_types tests/test_typechecker.py::TestTypecheck::test_various tests/test_typechecker.py::TestTypecheck_class::test_classmethod tests/test_typechecker.py::TestTypecheck_class::test_method tests/test_typechecker.py::TestTypecheck_class::test_staticmethod tests/test_typechecker.py::TestTypecheck_module::test_function_py2 tests/test_typechecker.py::TestTypecheck_module::test_function_py3 tests/test_typechecker.py::Test_check_argument_types::test_function tests/test_typechecker.py::Test_check_argument_types::test_inner_class tests/test_typechecker.py::Test_check_argument_types::test_inner_method tests/test_typechecker.py::Test_check_argument_types::test_methods tests/test_typechecker.py::TestOverride::test_auto_override tests/test_typechecker.py::TestOverride::test_override tests/test_typechecker.py::TestOverride::test_override_at_definition_time tests/test_typechecker.py::TestOverride::test_override_at_definition_time_with_forward_decl tests/test_typechecker.py::TestOverride::test_override_diamond tests/test_typechecker.py::TestOverride::test_override_typecheck tests/test_typechecker.py::TestOverride::test_override_typecheck_class tests/test_typechecker.py::TestOverride::test_override_vararg tests/test_typechecker.py::TestStubfile::test_annotations_from_stubfile_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_annotations_from_stubfile_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_callable_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_custom_generic_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_defaults_inferred_types_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_defaults_inferred_types_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_dict_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_generator_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_iterable_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_override_diamond_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_override_diamond_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_property_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_property_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_sequence_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_typecheck_parent_type_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_typecheck_parent_type_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_varargs_check_argument_types_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_varargs_check_argument_types_plain_3_5_stub tests/test_typechecker.py::TestStubfile::test_varargs_plain_2_7_stub tests/test_typechecker.py::TestStubfile::test_varargs_plain_3_5_stub tests/test_typechecker.py::TestTypecheck_Python3_5::test_abstract_override_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_callable_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_classmethod_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_custom_generic_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_defaults_inferred_types tests/test_typechecker.py::TestTypecheck_Python3_5::test_dict_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_function_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_generator_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_get_types_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_iterable_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_method_forward_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_method_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_parent_typecheck_no_override_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_parent_typecheck_other_signature_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_property tests/test_typechecker.py::TestTypecheck_Python3_5::test_sequence_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_staticmethod_py3 tests/test_typechecker.py::TestTypecheck_Python3_5::test_typecheck_parent_type tests/test_typechecker.py::TestTypecheck_Python3_5::test_typevar_func tests/test_typechecker.py::TestTypecheck_Python3_5::test_varargs tests/test_typechecker.py::TestTypecheck_Python3_5::test_varargs_check_argument_types tests/test_typechecker.py::TestTypecheck_Python3_5::test_various_py3 tests/test_typechecker.py::TestOverride_Python3_5::test_auto_override tests/test_typechecker.py::TestOverride_Python3_5::test_override_at_definition_time tests/test_typechecker.py::TestOverride_Python3_5::test_override_at_definition_time_with_forward_decl tests/test_typechecker.py::TestOverride_Python3_5::test_override_diamond tests/test_typechecker.py::TestOverride_Python3_5::test_override_py3 tests/test_typechecker.py::TestOverride_Python3_5::test_override_typecheck tests/test_typechecker.py::TestOverride_Python3_5::test_override_vararg tests/test_typechecker.py::Test_check_argument_types_Python3_5::test_function tests/test_typechecker.py::Test_check_argument_types_Python3_5::test_inner_class tests/test_typechecker.py::Test_check_argument_types_Python3_5::test_inner_method tests/test_typechecker.py::Test_check_argument_types_Python3_5::test_methods
pytypes/type_util.py
pytypes/type_util.py