diff --git a/src/MetaModels/DataAccess/ItemPersister.php b/src/MetaModels/DataAccess/ItemPersister.php
index 2759bd085..3ed2730f0 100644
--- a/src/MetaModels/DataAccess/ItemPersister.php
+++ b/src/MetaModels/DataAccess/ItemPersister.php
@@ -191,7 +191,7 @@ private function createNewItem(IItem $item)
             ->set($data)
             ->execute()
             ->insertId;
-        $item->set('id', $itemId);
+        $item->set('id', (string) $itemId);
 
         // Set the variant group equal to the id.
         if ($isNewBaseItem) {