diff --git a/core/lib/Drupal/Core/Bootstrap/Bootstrap.php b/core/lib/Drupal/Core/Bootstrap/Bootstrap.php
index 789310a..36659af 100644
--- a/core/lib/Drupal/Core/Bootstrap/Bootstrap.php
+++ b/core/lib/Drupal/Core/Bootstrap/Bootstrap.php
@@ -30,7 +30,7 @@ class Bootstrap {
    *   TRUE if there is sufficient memory to allow the operation, or FALSE
    *   otherwise.
    */
-  function checkMemoryLimit($required, $memory_limit = NULL) {
+  public static function checkMemoryLimit($required, $memory_limit = NULL) {
     if (!isset($memory_limit)) {
       $memory_limit = ini_get('memory_limit');
     }
@@ -78,7 +78,7 @@ function checkMemoryLimit($required, $memory_limit = NULL) {
    * @see request_uri()
    * @see \Symfony\Component\HttpFoundation\Request::getClientIP()
    */
-  function overrideServerVariables($variables = array()) {
+  public static function overrideServerVariables($variables = array()) {
     // Allow the provided URL to override any existing values in $_SERVER.
     if (isset($variables['url'])) {
       $url = parse_url($variables['url']);