diff --git a/test/test_persistent_dict.py b/test/test_persistent_dict.py
index bf1fd5433bb88524fdc75bdbf5c62497c3868563..050d9d951092d5abb0f136e5241427d780e3a909 100644
--- a/test/test_persistent_dict.py
+++ b/test/test_persistent_dict.py
@@ -58,7 +58,8 @@ def test_persistent_dict_storage_and_lookup():
                     for i in range(n))
 
         keys = [
-                (randrange(2000), rand_str(), None, SomeTag(rand_str()))
+                (randrange(2000)-1000, rand_str(), None, SomeTag(rand_str()),
+                    frozenset({"abc", 123}))
                 for i in range(20)]
         values = [randrange(2000) for i in range(20)]