diff --git a/tests/ProductTypeDiscountConstraintTest.php b/tests/ProductTypeDiscountConstraintTest.php
index b3dddeb..564b7da 100644
--- a/tests/ProductTypeDiscountConstraintTest.php
+++ b/tests/ProductTypeDiscountConstraintTest.php
@@ -23,7 +23,7 @@ public function setUp(): void
     {
         parent::setUp();
         ShopTest::setConfiguration();
-        Config::inst()->update(Discount::class, 'constraints',
+        Config::inst()->merge(Discount::class, 'constraints',
             [
             'ProductTypeDiscountConstraint'
             ]