diff --git a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
index a0f817f..fca0dd1 100644
--- a/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
+++ b/core/lib/Drupal/Core/Cache/Context/QueryArgsCacheContext.php
@@ -30,12 +30,11 @@ public static function getLabel() {
    */
   public function getContext($query_arg = NULL) {
     if ($query_arg === NULL) {
-      $query_string = $this->requestStack->getCurrentRequest()->getQueryString();
-      return (string) $query_string;
+      return (string) $this->requestStack->getCurrentRequest()->getQueryString();
     }
 
     $value = $this->requestStack->getCurrentRequest()->query->get($query_arg, NULL, TRUE);
-    return (string) http_build_query([$query_arg => $value], '', '&');
+    return http_build_query([$query_arg => $value], '', '&');
   }
 
   /**