diff --git a/backend/app/plugins/wiaas/includes/class-wiaas-checkout.php b/backend/app/plugins/wiaas/includes/class-wiaas-checkout.php
index 0cd07f4..e202e1a 100644
--- a/backend/app/plugins/wiaas/includes/class-wiaas-checkout.php
+++ b/backend/app/plugins/wiaas/includes/class-wiaas-checkout.php
@@ -2,6 +2,22 @@
 
 class Wiaas_Checkout {
 
+	public static function init(){
+		add_action( 'woocommerce_before_checkout_process', array(__CLASS__, 'validate_wiaas_packages'));
+	}
+
+	public static function validate_wiaas_packages(){
+		//check if any package became invalid
+		$items = WC()->cart->get_cart();
+		foreach($items as $item) { 
+			$item_id =  $item['data']->get_id();
+			if (wc_pb_is_bundle_container_cart_item($item) && 
+				(Wiaas_Package_Status::get_package_status($item_id) !== Wiaas_Package_Status::AVAILABLE)){
+					throw new Exception('Package ' . $item['data']->get_title() . ' cannot be purchased at the moment');
+			}	
+		}
+	}
+
 	/**
 	 * Process the order checkout.
 	 *
@@ -18,16 +34,6 @@ class Wiaas_Checkout {
 			do_action( 'woocommerce_before_checkout_process' );
 			$customer = wp_get_current_user();
 
-			//check if any package became invalid
-			$items = WC()->cart->get_cart();
-			foreach($items as $item) { 
-				$item_id =  $item['data']->get_id();
-				if (wc_pb_is_bundle_container_cart_item($item) && 
-					(Wiaas_Package_Status::get_package_status($item_id) !== Wiaas_Package_Status::AVAILABLE)){
-						throw new Exception('Package ' . $item['data']->get_title() . ' cannot be purchased at the moment');
-				}	
-			}
-
 			$order_id = WC()->checkout()->create_order(array());
 			$order = wc_get_order( $order_id );
 
@@ -101,3 +107,5 @@ class Wiaas_Checkout {
 		}
 	}
 }
+
+Wiaas_Checkout::init();