diff --git a/koha-tmpl/intranet-tmpl/prog/js/pages/preferences.js b/koha-tmpl/intranet-tmpl/prog/js/pages/preferences.js
index 7823d49d72..2ac7adefac 100644
--- a/koha-tmpl/intranet-tmpl/prog/js/pages/preferences.js
+++ b/koha-tmpl/intranet-tmpl/prog/js/pages/preferences.js
@@ -89,6 +89,7 @@ function addExpandHandler() {
             $(this).hide();
             var target = $(this).data("target");
             var syntax = $(this).data("syntax");
+            var lint_type = syntax === 'javascript'? { 'esversion': 6 } : true;
             $("#collapse_" + target).show();
             if (syntax) {
                 var editor = CodeMirror.fromTextArea(document.getElementById("pref_" + target), {
@@ -97,7 +98,7 @@ function addExpandHandler() {
                     lineWrapping: true,
                     viewportMargin: Infinity,
                     gutters: ["CodeMirror-lint-markers"],
-                    lint: true
+                    lint: lint_type,
                 });
                 editor.on("change", function () {
                     mark_modified.call($("#pref_" + target)[0]);