diff --git a/src/Sasedev/MpdfBundle/SasedevMpdfBundle.php b/src/Sasedev/MpdfBundle/SasedevMpdfBundle.php
index 0778ef6..d4d539d 100644
--- a/src/Sasedev/MpdfBundle/SasedevMpdfBundle.php
+++ b/src/Sasedev/MpdfBundle/SasedevMpdfBundle.php
@@ -3,7 +3,7 @@
 
 use Sasedev\MpdfBundle\DependencyInjection\SasedevMpdfExtension;
 use Symfony\Component\HttpKernel\Bundle\Bundle;
-
+use Symfony\Component\DependencyInjection\Extension\ExtensionInterface;
 /**
  *
  * Sasedev\MpdfBundle\SasedevMpdfBundle
@@ -20,7 +20,7 @@ class SasedevMpdfBundle extends Bundle
      * {@inheritdoc}
      * @see \Symfony\Component\HttpKernel\Bundle\Bundle::getContainerExtension()
      */
-    public function getContainerExtension()
+    public function createContainerExtension(): ?ExtensionInterface
     {
 
         return new SasedevMpdfExtension();