diff --git a/src/Sylius/Bundle/CoreBundle/Fixture/PaymentMethodFixture.php b/src/Sylius/Bundle/CoreBundle/Fixture/PaymentMethodFixture.php
index d3eb6083e6c..c1d0b80aa34 100644
--- a/src/Sylius/Bundle/CoreBundle/Fixture/PaymentMethodFixture.php
+++ b/src/Sylius/Bundle/CoreBundle/Fixture/PaymentMethodFixture.php
@@ -38,7 +38,7 @@ protected function configureResourceNode(ArrayNodeDefinition $resourceNode)
                 ->scalarNode('description')->cannotBeEmpty()->end()
                 ->scalarNode('gatewayName')->cannotBeEmpty()->end()
                 ->scalarNode('gatewayFactory')->cannotBeEmpty()->end()
-                ->arrayNode('gatewayConfig')->cannotBeEmpty()->end()
+                ->arrayNode('gatewayConfig')->prototype('variable')->end()->end()
                 ->arrayNode('channels')->prototype('scalar')->end()->end()
                 ->booleanNode('enabled')->end()
         ;
diff --git a/src/Sylius/Bundle/CoreBundle/Tests/Fixture/PaymentMethodFixtureTest.php b/src/Sylius/Bundle/CoreBundle/Tests/Fixture/PaymentMethodFixtureTest.php
index f991168328e..ce52d623ee6 100644
--- a/src/Sylius/Bundle/CoreBundle/Tests/Fixture/PaymentMethodFixtureTest.php
+++ b/src/Sylius/Bundle/CoreBundle/Tests/Fixture/PaymentMethodFixtureTest.php
@@ -72,6 +72,15 @@ public function payment_method_gateway_configuration_is_optional()
         $this->assertConfigurationIsValid([['custom' => [['gatewayConfig' => []]]]], 'custom.*.gatewayConfig');
     }
 
+    /**
+     * @test
+     */
+    public function payment_method_gateway_configuration_must_by_array()
+    {
+        $this->assertConfigurationIsValid([['custom' => [['gatewayConfig' => ['username' => 'USERNAME']]]]], 'custom.*.gatewayConfig');
+        $this->assertConfigurationIsInvalid([['custom' => [['gatewayConfig' => 'USERNAME']]]], 'Invalid type for path "payment_method.custom.0.gatewayConfig". Expected array, but got string');
+    }
+
     /**
      * @test
      */