diff --git a/docs/examples/04-adding-your-own-tag.php b/docs/examples/04-adding-your-own-tag.php
index 2e7ff75e..63dbb2f3 100644
--- a/docs/examples/04-adding-your-own-tag.php
+++ b/docs/examples/04-adding-your-own-tag.php
@@ -53,7 +53,7 @@ final class MyTag extends BaseTag
      *
      * @see BaseTag for the declaration of the description property and getDescription method.
      */
-    public function __construct(Description $description = null)
+    public function __construct(?Description $description = null)
     {
         $this->description = $description;
     }