diff --git a/lib/browser.js b/lib/browser.js
index 3161f78..6e8902a 100644
--- a/lib/browser.js
+++ b/lib/browser.js
@@ -7,10 +7,10 @@ var util = require('./util'),
     dataset = require('./dataset');
 /* HEADER END */
 
-var msiePattern = /MSIE ([.0-9]+);/;
-var tridentPattern = /Trident\/[.0-9]+;/;
-var tridentVersionPattern = / rv:([.0-9]+)/;
-var iemobilePattern = /IEMobile\/([.0-9]+);/;
+const msiePattern = /MSIE ([.0-9]+);/;
+const tridentPattern = /Trident\/[.0-9]+;/;
+const tridentVersionPattern = / rv:([.0-9]+)/;
+const iemobilePattern = /IEMobile\/([.0-9]+);/;
 var challengeMSIE = exports.challengeMSIE = function(ua, result) {
   if (ua.indexOf('compatible; MSIE') < 0 && ua.indexOf('Trident/') < 0 && ua.indexOf('IEMobile/'))
     return false;
@@ -32,7 +32,7 @@ var challengeMSIE = exports.challengeMSIE = function(ua, result) {
   return true;
 };
 
-var yandexBrowserPattern = /YaBrowser\/([.0-9]+)/;
+const yandexBrowserPattern = /YaBrowser\/([.0-9]+)/;
 var challengeYandexBrowser = exports.challengeYandexBrowser = function(ua, result) {
   if (ua.indexOf('YaBrowser/') < 0)
     return false;
@@ -49,12 +49,13 @@ var challengeYandexBrowser = exports.challengeYandexBrowser = function(ua, resul
   return true;
 };
 
-var edgePattern = /(?:Edge|Edg|EdgiOS|EdgA)\/([.0-9]+)/;
-var firefoxiOSPattern = /FxiOS\/([.0-9]+)/;
-var chromePattern = /(?:Chrome|CrMo|CriOS)\/([.0-9]+)/;
-var operaBlinkPattern = /OPR\/([.0-9]+)/;
-var gsaPattern = /GSA\/([.0-9]+)/;
-var safariPattern = /Version\/([.0-9]+)/;
+const edgePattern = /(?:Edge|Edg|EdgiOS|EdgA)\/([.0-9]+)/;
+const firefoxiOSPattern = /FxiOS\/([.0-9]+)/;
+const chromePattern = /(?:Chrome|CrMo|CriOS)\/([.0-9]+)/;
+const operaBlinkPattern = /OPR\/([.0-9]+)/;
+const gsaPattern = /GSA\/([.0-9]+)/;
+const safariPattern = /Version\/([.0-9]+)/;
+
 var challengeSafariChrome = exports.challengeSafariChrome = function(ua, result) {
   if (ua.indexOf('Safari/') < 0)
     return false;
@@ -202,7 +203,7 @@ var challengeSleipnir = exports.challengeSleipnir = function(ua, result) {
   return true;
 };
 
-var vivaldiPattern = /Vivaldi\/([.0-9]+)/;
+const vivaldiPattern = /Vivaldi\/([.0-9]+)/;
 var challengeVivaldi = exports.challengeVivaldi = function(ua, result) {
   if (ua.indexOf('Vivaldi/') < 0)
     return false;