diff --git a/src/WPDesk/Notice/AjaxHandler.php b/src/WPDesk/Notice/AjaxHandler.php
index 64c871754f1cfab287f9bfaff40f13a22ed72dae..fc3e67448b96feb7f5d9429f160eea140c1472c0 100644
--- a/src/WPDesk/Notice/AjaxHandler.php
+++ b/src/WPDesk/Notice/AjaxHandler.php
@@ -79,7 +79,7 @@ class AjaxHandler implements HookablePluginDependant {
             $noticeName = sanitize_text_field( $_POST[ self::POST_FIELD_NOTICE_NAME ] );
 
             $option_name = PermanentDismissibleNotice::OPTION_NAME_PREFIX . $noticeName;
-            ajax_check_referer( $option_name, self::POST_FIELD_SECURITY );
+            \ajax_check_referer( $option_name, self::POST_FIELD_SECURITY );
 
             if ( ! current_user_can( 'edit_posts' ) ) {
                 wp_send_json_error();