diff --git a/src/Symfony/Component/DependencyInjection/DefinitionDecorator.php b/src/Symfony/Component/DependencyInjection/DefinitionDecorator.php
index 9fa67439b91e8..f23f854481feb 100644
--- a/src/Symfony/Component/DependencyInjection/DefinitionDecorator.php
+++ b/src/Symfony/Component/DependencyInjection/DefinitionDecorator.php
@@ -13,6 +13,10 @@
 
 @trigger_error('The '.__NAMESPACE__.'\DefinitionDecorator class is deprecated since version 3.3 and will be removed in 4.0. Use the Symfony\Component\DependencyInjection\ChildDefinition class instead.', E_USER_DEPRECATED);
 
+class_exists(ChildDefinition::class);
+
+return;
+
 /**
  * This definition decorates another definition.
  *
@@ -20,4 +24,6 @@
  *
  * @deprecated The DefinitionDecorator class is deprecated since version 3.3 and will be removed in 4.0. Use the Symfony\Component\DependencyInjection\ChildDefinition class instead.
  */
-class_exists(ChildDefinition::class);
+class DefinitionDecorator extends Definition
+{
+}