diff --git a/Models/Invoice.php b/Models/Invoice.php
index fa3c0a4..1868c21 100644
--- a/Models/Invoice.php
+++ b/Models/Invoice.php
@@ -25,7 +25,7 @@ use phpOMS\Localization\Money;
  * @link       http://website.orange-management.de
  * @since      1.0.0
  */
-final class Invoice implements \JsonSerializable
+class Invoice implements \JsonSerializable
 {
     private $id = 0;
 
diff --git a/Models/InvoiceElement.php b/Models/InvoiceElement.php
index 407eebb..78d33dc 100644
--- a/Models/InvoiceElement.php
+++ b/Models/InvoiceElement.php
@@ -22,7 +22,7 @@ namespace Modules\Billing\Models;
  * @link       http://website.orange-management.de
  * @since      1.0.0
  */
-final class InvoiceElement implements \JsonSerializable
+class InvoiceElement implements \JsonSerializable
 {
     private $id = 0;