diff --git a/composer.json b/composer.json
index 86ca4a1..1441abd 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
     "name": "buckaroo/sdk",
     "description": "Buckaroo payment SDK",
     "license": "MIT",
-    "version": "1.21.0",
+    "version": "1.21.1",
     "type": "library",
     "require": {
         "php": ">=7.4|^8.0",
diff --git a/src/PaymentMethods/Subscriptions/Models/RatePlanCharge.php b/src/PaymentMethods/Subscriptions/Models/RatePlanCharge.php
index 4303aee..586df3a 100644
--- a/src/PaymentMethods/Subscriptions/Models/RatePlanCharge.php
+++ b/src/PaymentMethods/Subscriptions/Models/RatePlanCharge.php
@@ -24,6 +24,11 @@
 
 class RatePlanCharge extends ServiceParameter
 {
+    /**
+     * @var string
+     */
+    protected string $ratePlanChargeGuid;
+    
     /**
      * @var string
      */
diff --git a/src/PaymentMethods/iDeal/Models/Pay.php b/src/PaymentMethods/iDeal/Models/Pay.php
index 5c0ed0e..04d6616 100644
--- a/src/PaymentMethods/iDeal/Models/Pay.php
+++ b/src/PaymentMethods/iDeal/Models/Pay.php
@@ -24,6 +24,6 @@
 
 class Pay extends ServiceParameter
 {
-    protected string $issuer;
+    protected ?string $issuer = null;
     protected string $shippingCost;
 }