diff --git a/services/nginx/app/objects/collected_order_invoices_o.php b/services/nginx/app/objects/collected_order_invoices_o.php
index 55255c36..5e0329d0 100644
--- a/services/nginx/app/objects/collected_order_invoices_o.php
+++ b/services/nginx/app/objects/collected_order_invoices_o.php
@@ -986,6 +986,8 @@ class collected_order_invoices_o extends db
                 $free_subscription_addons = [
                     23, // Spot Free- Varevogn
                     24, // Spot Free- Lastbil
+                    21, // Undervognsskyld pr. enhed.
+
                 ];
                 if (in_array($addon['product_id'], $free_subscription_addons)) {
                     $tmp_subscription_price = 0;