diff --git a/Models/Invoice.php b/Models/Invoice.php
index 622da65..4ded331 100644
--- a/Models/Invoice.php
+++ b/Models/Invoice.php
@@ -30,7 +30,7 @@ class Invoice implements \JsonSerializable
     /**
      * Number ID.
      *
-     * @var int
+     * @var string
      * @since 1.0.0
      */
     private $number = '';