diff --git a/src/wp-includes/class-wp-customize-section.php b/src/wp-includes/class-wp-customize-section.php
index 3012547504..7af62189e6 100644
--- a/src/wp-includes/class-wp-customize-section.php
+++ b/src/wp-includes/class-wp-customize-section.php
@@ -529,7 +529,7 @@ class WP_Customize_Nav_Menu_Section extends WP_Customize_Section {
 	 *
 	 * @return array
 	 */
-	function json() {
+	public function json() {
 		$exported = parent::json();
 		$exported['menu_id'] = intval( preg_replace( '/^nav_menu\[(\d+)\]/', '$1', $this->id ) );