diff --git a/core/lib/Drupal/Core/Render/Element/Markup.php b/core/lib/Drupal/Core/Render/Element/Markup.php
index c1763a6..e9b04d2 100644
--- a/core/lib/Drupal/Core/Render/Element/Markup.php
+++ b/core/lib/Drupal/Core/Render/Element/Markup.php
@@ -47,7 +47,7 @@
  * );
  * $output['escaped_string'] = array(
  *   '#type' => 'markup',
- *   '#text_plain' => '<em>This is escaped</em>',
+ *   '#plain_text' => '<em>This is escaped</em>',
  * );
  * @endcode
  *