diff --git a/tpl/macro.twig b/tpl/macro.twig
index b4403fb..e0cbce8 100644
--- a/tpl/macro.twig
+++ b/tpl/macro.twig
@@ -447,7 +447,8 @@ public class {{o.name}} : IRpc
     //old items leftovers are considered removed
     for(; old_i < old_items.Count; old_i++)
     {
-      removed.Add(old_items[old_i].MakeId());
+      if(removed != null)
+        removed.Add(old_items[old_i].MakeId());
       has_diff = true;
     }