diff --git a/test/test_cast.py b/test/test_cast.py
index a73f21a..517f239 100644
--- a/test/test_cast.py
+++ b/test/test_cast.py
@@ -192,4 +192,8 @@ def obj_value(obj):
         text = hipack.dumps({"item": h}, value=obj_value)
         self.assertEqual(six.u(expected), _U(text))
 
+    def test_serialize_duplicate_annotation(self):
+        with self.assertRaises(ValueError):
+            hipack.dumps({"x":0}, value=lambda x: (x, ("a", "a")))
+
 unpack_data(TestValue)