diff --git a/tests/Rector/Class_/ParentClassToTraitsRector/config.yml b/tests/Rector/Class_/ParentClassToTraitsRector/config.yml
index 5e9f0f84b9f..100fe7e1317 100644
--- a/tests/Rector/Class_/ParentClassToTraitsRector/config.yml
+++ b/tests/Rector/Class_/ParentClassToTraitsRector/config.yml
@@ -1,10 +1,9 @@
 services:
     Rector\Rector\Class_\ParentClassToTraitsRector:
-        arguments:
-            $parentClassToTraits:
-                'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\ParentObject':
-                    - 'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\SomeTrait'
-                'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\AnotherParentObject':
-                    - 'SilverStripe\Core\Extensible'
-                    - 'SilverStripe\Core\Injector\Injectable'
-                    - 'SilverStripe\Core\Config\Configurable'
+        $parentClassToTraits:
+            'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\ParentObject':
+                - 'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\SomeTrait'
+            'Rector\Tests\Rector\Class_\ParentClassToTraitsRector\Source\AnotherParentObject':
+                - 'SilverStripe\Core\Extensible'
+                - 'SilverStripe\Core\Injector\Injectable'
+                - 'SilverStripe\Core\Config\Configurable'