diff --git a/src/Libs/ModelMySQL.php b/src/Libs/ModelMySQL.php
index 87c683e..3d5fa9d 100644
--- a/src/Libs/ModelMySQL.php
+++ b/src/Libs/ModelMySQL.php
@@ -17,7 +17,7 @@ use mysqli;
 
 class ModelMySQL {
 
-    public           int     $id;
+    public           ?int    $id          = null;
     protected        array   $toNull      = [];
     static protected string  $primaryKey  = 'id';
     static protected array   $ignoreSave  = ['id'];