diff --git a/src/groq/_utils/_transform.py b/src/groq/_utils/_transform.py
index 5207549..f70b4b6 100644
--- a/src/groq/_utils/_transform.py
+++ b/src/groq/_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 not args:
+            return 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 not args:
+            return 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 affc3ee..8807fa0 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -453,6 +453,15 @@ async def test_strips_notgiven(use_async: bool) -> None:
     assert await transform({"foo_bar": not_given}, Foo1, use_async) == {}
 
 
+@parametrize
+@pytest.mark.asyncio
+async def test_bare_dict_annotation_no_indexerror(use_async: bool) -> None:
+    # A bare `dict` annotation (no type args) previously raised IndexError because
+    # get_args(dict) returns () and the code unconditionally indexed [1].
+    result = await transform({"key": {"a": 1}}, Annotated[dict, PropertyInfo(alias="key")], use_async)
+    assert result == {"key": {"a": 1}}
+
+
 @parametrize
 @pytest.mark.asyncio
 async def test_strips_omit(use_async: bool) -> None: