diff --git a/configuration/micro_kernel_trait.rst b/configuration/micro_kernel_trait.rst
index 3dabb98a436..1d0dbe1a2d7 100644
--- a/configuration/micro_kernel_trait.rst
+++ b/configuration/micro_kernel_trait.rst
@@ -23,6 +23,7 @@ via Composer:
 
 Next, create an ``index.php`` file that creates a kernel class and executes it::
 
+    // index.php
     use Symfony\Bundle\FrameworkBundle\Kernel\MicroKernelTrait;
     use Symfony\Component\Config\Loader\LoaderInterface;
     use Symfony\Component\DependencyInjection\ContainerBuilder;