diff --git a/src/openai/_utils/_transform.py b/src/openai/_utils/_transform.py
index 414f38c340..6061e38c3e 100644
--- a/src/openai/_utils/_transform.py
+++ b/src/openai/_utils/_transform.py
@@ -180,8 +180,11 @@ def _transform_recursive(
         return _transform_typeddict(data, stripped_type)
 
     if origin == dict and is_mapping(data):
-        items_type = get_args(stripped_type)[1]
-        return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
+        args = get_args(stripped_type)
+        if len(args) >= 2:
+            items_type = args[1]
+            return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
+        return data
 
     if (
         # List[T]
@@ -346,8 +349,11 @@ 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]
-        return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
+        args = get_args(stripped_type)
+        if len(args) >= 2:
+            items_type = args[1]
+            return {key: _transform_recursive(value, annotation=items_type) for key, value in data.items()}
+        return data
 
     if (
         # List[T]
diff --git a/tests/test_transform.py b/tests/test_transform.py
index bece75dfc7..4f50799572 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -458,3 +458,16 @@ async def test_strips_notgiven(use_async: bool) -> None:
 async def test_strips_omit(use_async: bool) -> None:
     assert await transform({"foo_bar": "bar"}, Foo1, use_async) == {"fooBar": "bar"}
     assert await transform({"foo_bar": omit}, Foo1, use_async) == {}
+
+
+class TypedDictBareDict(TypedDict):
+    metadata: dict  # bare dict, no type parameters
+
+
+@parametrize
+@pytest.mark.asyncio
+async def test_bare_dict_no_indexerror(use_async: bool) -> None:
+    # bare `dict` annotation (no type params) must not raise IndexError
+    assert await transform({"metadata": {"key": "value"}}, TypedDictBareDict, use_async) == {
+        "metadata": {"key": "value"}
+    }