diff --git a/core/includes/bootstrap.inc b/core/includes/bootstrap.inc
index 4ebe881..69c8a33 100644
--- a/core/includes/bootstrap.inc
+++ b/core/includes/bootstrap.inc
@@ -889,7 +889,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
     $files[$type] = array();
   }
 
-  if (!empty($filename) && file_exists($filename)) {
+  if (isset($filename)) {
     $files[$type][$name] = $filename;
   }
   elseif (isset($files[$type][$name])) {
@@ -902,7 +902,7 @@ function drupal_get_filename($type, $name, $filename = NULL) {
     if (drupal_container()->has('keyvalue') && function_exists('db_query')) {
       try {
         $file_list = state()->get('system.' . $type . '.files');
-        if ($file_list && isset($file_list[$name]) && file_exists(DRUPAL_ROOT . '/' . $file_list[$name])) {
+        if ($file_list && isset($file_list[$name])) {
           $files[$type][$name] = $file_list[$name];
         }
       }
diff --git a/core/update.php b/core/update.php
index ff65c6e..a7cbf2d 100644
--- a/core/update.php
+++ b/core/update.php
@@ -330,10 +330,10 @@ function update_access_allowed() {
   if (!empty($update_free_access)) {
     return TRUE;
   }
-  // Calls to user_access() might fail during the Drupal 6 to 7 update process,
+  // Calls to user_access() might fail during the Drupal 7 to 8 update process,
   // so we fall back on requiring that the user be logged in as user #1.
   try {
-    require_once DRUPAL_ROOT . '/' . drupal_get_path('module', 'user') . '/user.module';
+    require_once DRUPAL_ROOT . '/core/modules/user/user.module';
     return user_access('administer software updates');
   }
   catch (Exception $e) {