diff --git a/src/openai/_utils/_transform.py b/src/openai/_utils/_transform.py
index 414f38c340..7655e55fcc 100644
--- a/src/openai/_utils/_transform.py
+++ b/src/openai/_utils/_transform.py
@@ -180,7 +180,10 @@ def _transform_recursive(
         return _transform_typeddict(data, stripped_type)
 
     if origin == dict and is_mapping(data):
-        items_type = get_args(stripped_type)[1]
+        args = get_args(stripped_type)
+        if len(args) < 2:
+            return cast(object, data)
+        items_type = args[1]
         return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
 
     if (
@@ -346,7 +349,10 @@ async def _async_transform_recursive(
         return await _async_transform_typeddict(data, stripped_type)
 
     if origin == dict and is_mapping(data):
-        items_type = get_args(stripped_type)[1]
+        args = get_args(stripped_type)
+        if len(args) < 2:
+            return cast(object, data)
+        items_type = args[1]
         return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
 
     if (
diff --git a/tests/test_transform.py b/tests/test_transform.py
index bece75dfc7..483f87a8e9 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -397,6 +397,22 @@ class DictItems(TypedDict):
     assert await transform({"foo": {"foo_baz": "bar"}}, Dict[str, DictItems], use_async) == {"foo": {"fooBaz": "bar"}}
 
 
+
+class BareDictTypedDict(TypedDict, total=False):
+    metadata: dict  # bare dict — no type parameters
+
+
+@parametrize
+@pytest.mark.asyncio
+async def test_bare_dict_in_typeddict(use_async: bool) -> None:
+    """transform should not crash on bare dict annotations in TypedDict."""
+    result = await transform({"metadata": {"key": "value"}}, BareDictTypedDict, use_async)
+    assert result == {"metadata": {"key": "value"}}
+
+    result = await transform({"metadata": {}}, BareDictTypedDict, use_async)
+    assert result == {"metadata": {}}
+
+
 class TypedDictIterableUnionStr(TypedDict):
     foo: Annotated[Union[str, Iterable[Baz8]], PropertyInfo(alias="FOO")]