diff --git a/autoregistry/_registry.py b/autoregistry/_registry.py
index cec0091..759ffeb 100644
--- a/autoregistry/_registry.py
+++ b/autoregistry/_registry.py
@@ -202,14 +202,6 @@ def __new__(
         # Manipulate namespace instead of modifying attributes after calling __new__ so
         # that hooks like __init_subclass__ have appropriately set registry attributes.
         # Each subclass gets its own registry.
-        try:
-            Registry  # pyright: ignore[reportUnusedExpression]
-        except NameError:
-            # Should only happen the very first time that
-            # Registry is being defined.
-            namespace["__registry__"] = _Registry(RegistryConfig(**config))
-            new_cls = super().__new__(cls, cls_name, bases, namespace)
-            return new_cls
 
         # Copy the nearest parent config, then update it with new params
         for parent_cls in bases:
@@ -219,7 +211,10 @@ def __new__(
             except AttributeError:
                 pass
         else:
-            raise InternalError("Should never happen.")  # pragma: no cover
+            # No parent config, create a new one from scratch.
+            namespace["__registry__"] = _Registry(RegistryConfig(**config))
+            new_cls = super().__new__(cls, cls_name, bases, namespace)
+            return new_cls
 
         # Derive registry name before updating registry config, since a classes own name is
         # subject to it's parents configuration, not its own.
diff --git a/tests/test_meta_extension.py b/tests/test_meta_extension.py
new file mode 100644
index 0000000..c8e6e25
--- /dev/null
+++ b/tests/test_meta_extension.py
@@ -0,0 +1,26 @@
+from autoregistry import RegistryMeta
+
+
+class ExtendedRegistryMeta(RegistryMeta):
+    def __call__(cls, *args, **kwargs):  # noqa: N805
+        out = super().__call__(*args, **kwargs)
+        out.extended_attribute = cls.__name__
+        return out
+
+
+class Foo(metaclass=ExtendedRegistryMeta):
+    pass
+
+
+class Bar(Foo):
+    pass
+
+
+def test_extended_registry():
+    foo = Foo()
+    bar = Bar()
+
+    assert foo.extended_attribute == "Foo"
+    assert bar.extended_attribute == "Bar"
+
+    assert list(Foo) == ["bar"]