diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index d33d1ee..d5c2654 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -432,7 +432,6 @@ function _drupal_request_initialize() {
   global $base_url, $cookie_domain;
   // Set and derived from $base_url by this function.
   global $base_path, $base_root, $script_path;
-  global $base_secure_url, $base_insecure_url;
 
   $is_https = isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on';
 
@@ -472,8 +471,6 @@ function _drupal_request_initialize() {
       $base_path = '/';
     }
   }
-  $base_secure_url = str_replace('http://', 'https://', $base_url);
-  $base_insecure_url = str_replace('https://', 'http://', $base_url);
 
   // Determine the path of the script relative to the base path, and add a
   // trailing slash. This is needed for creating URLs to Drupal pages.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Session/SessionHttpsTest.php b/core/modules/system/lib/Drupal/system/Tests/Session/SessionHttpsTest.php
index 858da22..af153dd 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Session/SessionHttpsTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Session/SessionHttpsTest.php
@@ -319,11 +319,11 @@ protected function assertSessionIds($sid, $ssid, $assertion_text) {
    *   A Drupal path such as 'user'.
    *
    * @return
-   *   An absolute URL.
+   *   The URL prepared in a way such that the https.php mock front controller
+   *   is used.
    */
   protected function httpsUrl($url) {
-    global $base_url;
-    return $base_url . '/core/modules/system/tests/https.php/' . $url;
+    return 'core/modules/system/tests/https.php/' . $url;
   }
 
   /**
@@ -333,11 +333,11 @@ protected function httpsUrl($url) {
    *   A Drupal path such as 'user'.
    *
    * @return
-   *   An absolute URL.
+   *   The URL prepared in a way such that the http.php mock front controller is
+   *   used.
    */
   protected function httpUrl($url) {
-    global $base_url;
-    return $base_url . '/core/modules/system/tests/http.php/' . $url;
+    return 'core/modules/system/tests/http.php/' . $url;
   }
 
 }
diff --git a/core/modules/system/tests/modules/session_test/lib/Drupal/session_test/EventSubscriber/SessionTestSubscriber.php b/core/modules/system/tests/modules/session_test/lib/Drupal/session_test/EventSubscriber/SessionTestSubscriber.php
index 55225ae..4be74ae 100644
--- a/core/modules/system/tests/modules/session_test/lib/Drupal/session_test/EventSubscriber/SessionTestSubscriber.php
+++ b/core/modules/system/tests/modules/session_test/lib/Drupal/session_test/EventSubscriber/SessionTestSubscriber.php
@@ -49,12 +49,12 @@ public function onKernelResponseSessionTest(FilterResponseEvent $event) {
     if ($response instanceOf RedirectResponse) {
       // Force the redirection to go to a non-secure page after being on a
       // secure page through https.php.
-      global $base_insecure_url, $is_https_mock;
+      global $is_https_mock;
       // Alter the redirect to use HTTP when using a mock HTTPS request through
       // https.php because form submissions would otherwise redirect to a
       // non-existent HTTPS site.
       if (!empty($is_https_mock)) {
-        $path = $base_insecure_url . '/' . $response->getTargetUrl();
+        str_replace('https://', 'http://', $response->getTargetUrl());
         $response->setTargetUrl($path);
       }
     }