diff --git a/service_container/expression_language.rst b/service_container/expression_language.rst
index cbab6c2ffde..fe2edfdad88 100644
--- a/service_container/expression_language.rst
+++ b/service_container/expression_language.rst
@@ -60,7 +60,7 @@ to another service: ``App\Mailer``. One way to do this is with an expression:
         $container->autowire(MailerConfiguration::class);
 
         $container->autowire(Mailer::class)
-            ->addArgument(new Expression('service("App\Mail\MailerConfiguration").getMailerMethod()'));
+            ->addArgument(new Expression('service("App\\\\Mail\\\\MailerConfiguration").getMailerMethod()'));
 
 To learn more about the expression language syntax, see :doc:`/components/expression_language/syntax`.