diff --git a/src/wp-includes/class-wp-customize-control.php b/src/wp-includes/class-wp-customize-control.php
index 6e25eb04d6..c7bea17f6a 100644
--- a/src/wp-includes/class-wp-customize-control.php
+++ b/src/wp-includes/class-wp-customize-control.php
@@ -1637,7 +1637,7 @@ class WP_Customize_Nav_Menu_Item_Control extends WP_Customize_Control {
 	 *
 	 * @return array
 	 */
-	function json() {
+	public function json() {
 		$exported                 = parent::json();
 		$exported['menu_item_id'] = $this->setting->post_id;