# UNDF: UNDF-2026-000000950
--- a/src/tiled/mapobjectmodel.cpp
+++ b/src/tiled/mapobjectmodel.cpp
@@ -493,6 +493,7 @@ void MapObjectModel::classChanged(const QList<Object *> &objects)
     } else if (typeId == Object::TileType) {
+        const QSet<Object *> objectSet(objects.begin(), objects.end());
         for (const Layer *layer : map()->objectGroups()) {
             auto objectGroup = static_cast<const ObjectGroup*>(layer);
             for (MapObject *mapObject : objectGroup->objects()) {
                 if (mapObject->className().isEmpty())
                     if (auto tile = mapObject->cell().tile())
-                        if (objects.contains(tile))
+                        if (objectSet.contains(tile))
                             affectedObjects.append(mapObject);
             }
         }