diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index a7631f92e7ea81..a7b35be936f8d9 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -2138,6 +2138,22 @@ def test_bool_notimplemented(self):
         with self.assertRaisesRegex(TypeError, msg):
             not NotImplemented
 
+    def test_not_implemented(self):
+        self.assertIs(type(NotImplemented), NotImplemented.__class__)
+        self.assertIs(type(NotImplemented).__class__, type)
+
+        # Missing instance attributes:
+        with self.assertRaises(AttributeError):
+            NotImplemented.prop
+        with self.assertRaises(AttributeError):
+            NotImplemented.prop = 1
+
+        # Missing class attributes:
+        with self.assertRaises(AttributeError):
+            type(NotImplemented).prop
+        with self.assertRaises(TypeError):
+            type(NotImplemented).prop = 1
+
 
 class TestBreakpoint(unittest.TestCase):
     def setUp(self):