diff --git a/test/unit/list_test.rb b/test/unit/list_test.rb
index <HASH>..<HASH> 100644
--- a/test/unit/list_test.rb
+++ b/test/unit/list_test.rb
@@ -158,7 +158,8 @@ EOS
 
 
   def test_self_default_getter
-    assert_equal nil, PublicSuffix::List.class_eval { @default }
+    PublicSuffix::List.default = nil
+    assert_nil PublicSuffix::List.class_eval { @default; }
     PublicSuffix::List.default
     assert_not_equal nil, PublicSuffix::List.class_eval { @default }
   end
As we don't know test_self_default_getter will run, it must be set to nil