diff --git a/src/Form/Type/NewOrderType.php b/src/Form/Type/NewOrderType.php
index 8bf4d6fd..9d76ec8c 100644
--- a/src/Form/Type/NewOrderType.php
+++ b/src/Form/Type/NewOrderType.php
@@ -13,11 +13,13 @@
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\Form\FormEvent;
 use Symfony\Component\Form\FormEvents;
+use Symfony\Component\Validator\Constraints\Count;
 
 final class NewOrderType extends AbstractResourceType
 {
     public function buildForm(FormBuilderInterface $builder, array $options)
     {
+        $validationGroups = ['sylius'];
         $builder
             ->add('promotionCoupon', PromotionCouponToCodeType::class, [
                 'by_reference' => false,
@@ -37,6 +39,9 @@ public function buildForm(FormBuilderInterface $builder, array $options)
                 'allow_add' => true,
                 'allow_delete' => true,
                 'by_reference' => false,
+                'constraints' => [
+                    new Count(['min' => 1, 'max' => 1, 'groups' => $validationGroups]),
+                ],
             ])
             ->add('shipments', CollectionType::class, [
                 'entry_type' => ShipmentType::class,
diff --git a/src/Resources/config/validation.xml b/src/Resources/config/validation.xml
deleted file mode 100644
index 94a0075a..00000000
--- a/src/Resources/config/validation.xml
+++ /dev/null
@@ -1,16 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-
-<constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
-                    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-                    xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping
-                    http://symfony.com/schema/dic/services/constraint-mapping-1.0.xsd">
-    <class name="Sylius\Component\Core\Model\Order">
-        <property name="payments">
-            <constraint name="Count">
-                <option name="min">1</option>
-                <option name="max">1</option>
-                <option name="groups">sylius</option>
-            </constraint>
-        </property>
-    </class>
-</constraint-mapping>