diff --git a/core/modules/aggregator/tests/aggregator_test.module b/core/modules/aggregator/tests/aggregator_test.module
index 87081d7..6433950 100644
--- a/core/modules/aggregator/tests/aggregator_test.module
+++ b/core/modules/aggregator/tests/aggregator_test.module
@@ -35,8 +35,8 @@ function aggregator_test_feed($use_last_modified = FALSE, $use_etag = FALSE) {
   $last_modified = strtotime('Sun, 19 Nov 1978 05:00:00 GMT');
   $etag = Crypt::hashBase64($last_modified);

-  $if_modified_since = isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ? strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']) : FALSE;
-  $if_none_match = isset($_SERVER['HTTP_IF_NONE_MATCH']) ? stripslashes($_SERVER['HTTP_IF_NONE_MATCH']) : FALSE;
+  $if_modified_since = strtotime(Drupal::request()->server->get('HTTP_IF_MODIFIED_SINCE'));
+  $if_none_match = stripslashes(Drupal::request()->server->get('HTTP_IF_NONE_MATCH'));

   // Send appropriate response. We respond with a 304 not modified on either
   // etag or on last modified.