diff --git a/src/dropdown/dropdown.js b/src/dropdown/dropdown.js
index def60d197c..46816826bb 100644
--- a/src/dropdown/dropdown.js
+++ b/src/dropdown/dropdown.js
@@ -58,7 +58,7 @@ angular.module('ui.bootstrap.dropdown', ['ui.bootstrap.position'])
     if (evt.which === 27) {
       openScope.focusToggleElement();
       closeDropdown();
-    } else if (openScope.isKeynavEnabled() && /(38|40)/.test(evt.which) && openScope.isOpen) {
+    } else if (openScope.isKeynavEnabled() && [38, 40].indexOf(evt.which) !== -1 && openScope.isOpen) {
       evt.preventDefault();
       evt.stopPropagation();
       openScope.focusDropdownEntry(evt.which);