diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 301a2d2..0b43549 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -4647,9 +4647,11 @@
     def test_mixing_slot_wrappers(self):
         class X(dict):
             __setattr__ = dict.__setitem__
+            __neg__ = dict.copy
         x = X()
         x.y = 42
         self.assertEqual(x["y"], 42)
+        self.assertEqual(x, -x)
 
     def test_slot_shadows_class_variable(self):
         with self.assertRaises(ValueError) as cm: