diff --git a/js/skip-link-focus-fix.js b/js/skip-link-focus-fix.js
index a39cefbf..a40ebacf 100644
--- a/js/skip-link-focus-fix.js
+++ b/js/skip-link-focus-fix.js
@@ -5,12 +5,10 @@
  *
  * Learn more: https://git.io/vWdr2
  */
-( function() {
-	var isWebkit = navigator.userAgent.toLowerCase().indexOf( 'webkit' ) > -1,
-	    isOpera  = navigator.userAgent.toLowerCase().indexOf( 'opera' )  > -1,
-	    isIe     = navigator.userAgent.toLowerCase().indexOf( 'msie' )   > -1;
+(function() {
+	var isIe = /(trident|msie)/i.test( navigator.userAgent );
 
-	if ( ( isWebkit || isOpera || isIe ) && document.getElementById && window.addEventListener ) {
+	if ( isIe && document.getElementById && window.addEventListener ) {
 		window.addEventListener( 'hashchange', function() {
 			var id = location.hash.substring( 1 ),
 				element;