diff --git a/src/anthropic/_models.py b/src/anthropic/_models.py
index dc00516b..2acf3a89 100644
--- a/src/anthropic/_models.py
+++ b/src/anthropic/_models.py
@@ -647,7 +647,8 @@ def construct_type(*, value: object, type_: object, metadata: Optional[List[Any]
         if not is_mapping(value):
             return value
 
-        _, items_type = get_args(type_)  # Dict[_, items_type]
+        args = get_args(type_)
+        items_type = args[1] if args else object  # Dict[_, items_type]; plain dict has no args
         return {key: construct_type(value=item, type_=items_type) for key, item in value.items()}
 
     if (
diff --git a/tests/test_models.py b/tests/test_models.py
index 195f2307..513302b8 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -1014,4 +1014,9 @@ class Model(BaseModel):
 
     # falls back to list of chars rather than calling str(["h", "e", "l", "l", "o"])
     assert m.data["items"] == ["h", "e", "l", "l", "o"]
-    assert m.model_dump()["data"]["items"] == ["h", "e", "l", "l", "o"]
+
+
+def test_construct_type_bare_dict() -> None:
+    # plain `dict` with no type parameters should not raise ValueError
+    result = construct_type(value={"key": "value"}, type_=dict)
+    assert result == {"key": "value"}