diff --git a/test/driver.js b/test/driver.js
index 2eadf239e..0c8550486 100644
--- a/test/driver.js
+++ b/test/driver.js
@@ -405,14 +405,8 @@ var Driver = (function DriverClosure() {
 
   Driver.prototype = {
     _getQueryStringParameters: function Driver_getQueryStringParameters() {
-      var queryString = window.location.search.substring(1);
-      var values = queryString.split("&");
-      var parameters = {};
-      for (var i = 0, ii = values.length; i < ii; i++) {
-        var value = values[i].split("=");
-        parameters[unescape(value[0])] = unescape(value[1]);
-      }
-      return parameters;
+      const queryString = window.location.search.substring(1);
+      return Object.fromEntries(new URLSearchParams(queryString).entries());
     },
 
     run: function Driver_run() {
diff --git a/test/resources/reftest-analyzer.js b/test/resources/reftest-analyzer.js
index f97f3fb91..b0968dd09 100644
--- a/test/resources/reftest-analyzer.js
+++ b/test/resources/reftest-analyzer.js
@@ -53,11 +53,8 @@ window.onload = function () {
   function hashParameters() {
     const query = window.location.hash.substring(1);
     const params = new Map();
-    for (const part of query.split(/[&;]/)) {
-      const param = part.split("="),
-        key = param[0].toLowerCase(),
-        value = param.length > 1 ? param[1] : "";
-      params.set(decodeURIComponent(key), decodeURIComponent(value));
+    for (const [key, value] of new URLSearchParams(query)) {
+      params.set(key.toLowerCase(), value);
     }
     return params;
   }
diff --git a/web/ui_utils.js b/web/ui_utils.js
index 72ad3097b..4c9a057cc 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -187,11 +187,8 @@ function watchScroll(viewAreaElement, callback) {
  */
 function parseQueryString(query) {
   const params = new Map();
-  for (const part of query.split("&")) {
-    const param = part.split("="),
-      key = param[0].toLowerCase(),
-      value = param.length > 1 ? param[1] : "";
-    params.set(decodeURIComponent(key), decodeURIComponent(value));
+  for (const [key, value] of new URLSearchParams(query)) {
+    params.set(key.toLowerCase(), value);
   }
   return params;
 }