diff --git a/ormar/models/metaclass.py b/ormar/models/metaclass.py
index 88f5681..c9ac863 100644
--- a/ormar/models/metaclass.py
+++ b/ormar/models/metaclass.py
@@ -552,7 +552,13 @@ class ModelMetaclass(pydantic.main.ModelMetaclass):
         :param attrs: class namespace
         :type attrs: Dict
         """
-        attrs["Config"] = get_pydantic_base_orm_config()
+        if "Config" in attrs:
+            class Config(attrs["Config"], get_pydantic_base_orm_config()):
+                pass
+            attrs["Config"] = Config
+        else:
+            attrs["Config"] = get_pydantic_base_orm_config()
+
         attrs["__name__"] = name
         attrs, model_fields = extract_annotations_and_default_vals(attrs)
         for base in reversed(bases):
diff --git a/tests/test_inheritance_and_pydantic_generation/test_inheritance_concrete.py b/tests/test_inheritance_and_pydantic_generation/test_inheritance_concrete.py
index 41eac11..c655cf8 100644
--- a/tests/test_inheritance_and_pydantic_generation/test_inheritance_concrete.py
+++ b/tests/test_inheritance_and_pydantic_generation/test_inheritance_concrete.py
@@ -150,6 +150,12 @@ class Bus2(Car2):
     max_persons: int = ormar.Integer()
 
 
+class ImmutablePerson(Person):
+    class Config:
+        allow_mutation = False
+        validate_assignment = False
+
+
 @pytest.fixture(autouse=True, scope="module")
 def create_test_database():
     metadata.create_all(engine)
@@ -495,3 +501,13 @@ async def test_inheritance_with_multi_relation():
             assert len(unicorns) == 2
             assert unicorns[1].name == "Unicorn 2"
             assert len(unicorns[1].co_owners) == 1
+
+
+def test_custom_config():
+    # Custom config inherits defaults
+    assert getattr(ImmutablePerson.__config__, "orm_mode") == True
+    # Custom config can override defaults
+    assert getattr(ImmutablePerson.__config__, "validate_assignment") == False
+    sam = ImmutablePerson(name="Sam")
+    with pytest.raises(TypeError):
+        sam.name = "Not Sam"