diff --git a/app/Models/AfterSale.php b/app/Models/AfterSale.php
index 62df1830..1261bab6 100644
--- a/app/Models/AfterSale.php
+++ b/app/Models/AfterSale.php
@@ -152,6 +152,8 @@ class AfterSale extends Model
      */
     protected static function createSn()
     {
-        return 'AS'.now()->format('YmdHisu').strtoupper(Str::random(2));
+        $rand = strtoupper(Str::random(6));
+
+        return 'AS'.date('ymdHis').$rand;
     }
 }