diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 828f123491..26f9eb3a2c 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -5455,6 +5455,8 @@ function wp_delete_file( $file ) {
  * This prevents reusing the same tab for a preview when the user has navigated away.
  *
  * @since 4.3.0
+ *
+ * @global WP_Post $post
  */
 function wp_post_preview_js() {
 	global $post;