diff --git a/graphene_django_cud/mutations/batch_patch.py b/graphene_django_cud/mutations/batch_patch.py
index 4ee6e87..f620f32 100644
--- a/graphene_django_cud/mutations/batch_patch.py
+++ b/graphene_django_cud/mutations/batch_patch.py
@@ -17,8 +17,8 @@ def __init_subclass_with_meta__(
         cls,
         _meta=None,
         model=None,
-            optional_fields=(),
-            required_fields=(),
+            optional_fields=None,
+            required_fields=None,
         type_name=None,
         **kwargs,
     ):
@@ -35,8 +35,8 @@ def __init_subclass_with_meta__(
         return super().__init_subclass_with_meta__(
             _meta=_meta,
             model=model,
-            optional_fields=optional_fields,
-            required_fields=required_fields,
+            optional_fields=optional_fields or (),
+            required_fields=required_fields or (),
             type_name=input_type_name,
             **kwargs,
         )
diff --git a/graphene_django_cud/mutations/filter_update.py b/graphene_django_cud/mutations/filter_update.py
index 2d7e444..f5326ac 100644
--- a/graphene_django_cud/mutations/filter_update.py
+++ b/graphene_django_cud/mutations/filter_update.py
@@ -45,7 +45,7 @@ def __init_subclass_with_meta__(
         only_fields=(),  # Deprecated in favor of `fields`
         exclude=(),
         exclude_fields=(),  # Deprecated in favor of `exclude`
-            optional_fields=(),
+            optional_fields=None,  # Explicitly defaulted to None here and handled below.
         required_fields=(),
         field_types=None,
             auto_context_fields=None,
diff --git a/graphene_django_cud/mutations/patch.py b/graphene_django_cud/mutations/patch.py
index 77697b3..a51db20 100644
--- a/graphene_django_cud/mutations/patch.py
+++ b/graphene_django_cud/mutations/patch.py
@@ -17,8 +17,8 @@ def __init_subclass_with_meta__(
         cls,
         _meta=None,
         model=None,
-            optional_fields=(),
-            required_fields=(),
+            optional_fields=None,
+            required_fields=None,
         type_name=None,
         **kwargs,
     ):
@@ -35,8 +35,8 @@ def __init_subclass_with_meta__(
         return super().__init_subclass_with_meta__(
             _meta=_meta,
             model=model,
-            optional_fields=optional_fields,
-            required_fields=required_fields,
+            optional_fields=optional_fields or (),
+            required_fields=required_fields or (),
             type_name=input_type_name,
             **kwargs,
         )