diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
index 5e35a262d..12d8b289d 100644
--- a/Lib/test/test_types.py
+++ b/Lib/test/test_types.py
@@ -1191,7 +1191,6 @@ class ClassCreationTests(unittest.TestCase):
 
 class SimpleNamespaceTests(unittest.TestCase):
 
-    @unittest.skip("TODO: RUSTPYTHON")
     def test_constructor(self):
         ns1 = types.SimpleNamespace()
         ns2 = types.SimpleNamespace(x=1, y=2)
diff --git a/vm/src/frame.rs b/vm/src/frame.rs
index 81010b204..a3ed5ffdb 100644
--- a/vm/src/frame.rs
+++ b/vm/src/frame.rs
@@ -937,10 +937,15 @@ impl Frame {
                 let kwargs = if *has_kwargs {
                     let kw_dict: PyDictRef =
                         self.pop_value().downcast().expect("Kwargs must be a dict.");
-                    kw_dict
-                        .into_iter()
-                        .map(|elem| (objstr::clone_value(&elem.0), elem.1))
-                        .collect()
+                    let mut kwargs = IndexMap::new();
+                    for (key, value) in kw_dict.into_iter() {
+                        if let Some(key) = key.payload_if_subclass::<objstr::PyString>(vm) {
+                            kwargs.insert(key.as_str().to_owned(), value);
+                        } else {
+                            return Err(vm.new_type_error("keywords must be strings".to_owned()));
+                        }
+                    }
+                    kwargs
                 } else {
                     IndexMap::new()
                 };