diff --git a/modules/ppcp-api-client/src/Endpoint/IdentityToken.php b/modules/ppcp-api-client/src/Endpoint/IdentityToken.php
index ae12fdfca..ee43106ac 100644
--- a/modules/ppcp-api-client/src/Endpoint/IdentityToken.php
+++ b/modules/ppcp-api-client/src/Endpoint/IdentityToken.php
@@ -103,7 +103,7 @@ class IdentityToken {
 				WC()->session->set( 'ppcp_guest_customer_id', $customer_id );
 			}
 
-			$args['body'] = wp_json_encode( array( 'customer_id' => $this->prefix . $customer_id ) );
+			$args['body'] = wp_json_encode( array( 'customer_id' => $this->prefix . (string) $customer_id ) );
 		}
 
 		$response = $this->request( $url, $args );
diff --git a/modules/ppcp-vaulting/src/VaultingModule.php b/modules/ppcp-vaulting/src/VaultingModule.php
index bedaec1bc..d74dfc86e 100644
--- a/modules/ppcp-vaulting/src/VaultingModule.php
+++ b/modules/ppcp-vaulting/src/VaultingModule.php
@@ -101,10 +101,10 @@ class VaultingModule implements ModuleInterface {
 		$subscription_helper = $container->get( 'subscription.helper' );
 		add_action(
 			'woocommerce_created_customer',
-			function( $customer_id ) use ( $subscription_helper ) {
+			function( int $customer_id ) use ( $subscription_helper ) {
 				$guest_customer_id = WC()->session->get( 'ppcp_guest_customer_id' );
 				if ( $guest_customer_id && $subscription_helper->cart_contains_subscription() ) {
-					update_user_meta( $customer_id, 'ppcp_guest_customer_id', WC()->session->get( 'ppcp_guest_customer_id' ) );
+					update_user_meta( $customer_id, 'ppcp_guest_customer_id', $guest_customer_id );
 				}
 			}
 		);