diff --git a/src/anthropic/_models.py b/src/anthropic/_models.py
index dc00516bc..1d9ad6910 100644
--- a/src/anthropic/_models.py
+++ b/src/anthropic/_models.py
@@ -647,6 +647,9 @@ def construct_type(*, value: object, type_: object, metadata: Optional[List[Any]
         if not is_mapping(value):
             return value
 
+        if not args:
+            return value
+
         _, items_type = get_args(type_)  # Dict[_, items_type]
         return {key: construct_type(value=item, type_=items_type) for key, item in value.items()}
 
@@ -668,6 +671,9 @@ def construct_type(*, value: object, type_: object, metadata: Optional[List[Any]
         if not is_list(value):
             return value
 
+        if not args:
+            return value
+
         inner_type = args[0]  # List[inner_type]
         return [construct_type(value=entry, type_=inner_type) for entry in value]
 
diff --git a/src/anthropic/_utils/_transform.py b/src/anthropic/_utils/_transform.py
index 1e7e5ac80..72856b9a5 100644
--- a/src/anthropic/_utils/_transform.py
+++ b/src/anthropic/_utils/_transform.py
@@ -180,7 +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]
+        args = get_args(stripped_type)
+        if not args:
+            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 +350,11 @@ 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]
+        args = get_args(stripped_type)
+        if not args:
+            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_models.py b/tests/test_models.py
index 195f23079..99cd2d7aa 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -655,6 +655,14 @@ class Model(BaseModel):
     assert m.value == "foo"
 
 
+def test_construct_type_bare_container_types() -> None:
+    list_value = ["a", {"nested": "value"}]
+    dict_value = {"foo": ["bar"]}
+
+    assert construct_type(value=list_value, type_=list) is list_value
+    assert construct_type(value=dict_value, type_=dict) is dict_value
+
+
 def test_discriminated_unions_invalid_data() -> None:
     class A(BaseModel):
         type: Literal["a"]
diff --git a/tests/test_transform.py b/tests/test_transform.py
index 4a874ff86..9296118ee 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -397,6 +397,14 @@ class DictItems(TypedDict):
     assert await transform({"foo": {"foo_baz": "bar"}}, Dict[str, DictItems], use_async) == {"foo": {"fooBaz": "bar"}}
 
 
+@parametrize
+@pytest.mark.asyncio
+async def test_bare_dict_type(use_async: bool) -> None:
+    data = {"foo_bar": {"baz_qux": "value"}}
+
+    assert await transform(data, dict, use_async) is data
+
+
 class TypedDictIterableUnionStr(TypedDict):
     foo: Annotated[Union[str, Iterable[Baz8]], PropertyInfo(alias="FOO")]