diff --git a/core/lib/Drupal/Core/Routing/UrlGenerator.php b/core/lib/Drupal/Core/Routing/UrlGenerator.php
index c9521ed..9b7021b 100644
--- a/core/lib/Drupal/Core/Routing/UrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/UrlGenerator.php
@@ -235,8 +235,10 @@ protected function doGenerate(array $variables, array $defaults, array $tokens,
 
     // Add a query string if needed, including extra parameters.
     $query_params += array_diff_key($parameters, $variables, $defaults);
-    if ($query_params && $query = UrlHelper::buildQuery($query_params)) {
-      $url .= '?' . $query;
+    if ($query_params && $query = http_build_query($query_params, '', '&')) {
+      // "/" and "?" can be left decoded for better user experience, see
+      // http://tools.ietf.org/html/rfc3986#section-3.4
+      $url .= '?'.strtr($query, array('%2F' => '/'));
     }
 
     return $url;