diff --git a/core/includes/file.inc b/core/includes/file.inc
index 6e9c8e8..98904ff 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -452,8 +452,9 @@ function file_unmanaged_copy($source, $destination = NULL, $replace = FILE_EXIST
   }
   // Attempt to resolve the URIs. This is necessary in certain configurations
   // (see above).
-  $real_source = \Drupal::service('file_system')->realpath($source) ?: $source;
-  $real_destination = \Drupal::service('file_system')->realpath($destination) ?: $destination;
+  $file_system = \Drupal::service('file_system');
+  $real_source = $file_system->realpath($source) ?: $source;
+  $real_destination = $file_system->realpath($destination) ?: $destination;
   // Perform the copy operation.
   if (!@copy($real_source, $real_destination)) {
     \Drupal::logger('file')->error('The specified file %file could not be copied to %destination.', array('%file' => $source, '%destination' => $destination));
@@ -497,12 +498,13 @@ function file_unmanaged_copy($source, $destination = NULL, $replace = FILE_EXIST
 function file_unmanaged_prepare($source, &$destination = NULL, $replace = FILE_EXISTS_RENAME) {
   $original_source = $source;
   $logger = \Drupal::logger('file');
+  $file_system = \Drupal::service('file_system');
 
   // Assert that the source file actually exists.
   if (!file_exists($source)) {
     // @todo Replace drupal_set_message() calls with exceptions instead.
     drupal_set_message(t('The specified file %file could not be moved/copied because no file by that name exists. Please check that you supplied the correct filename.', array('%file' => $original_source)), 'error');
-    if (($realpath = \Drupal::service('file_system')->realpath($original_source)) !== FALSE) {
+    if (($realpath = $file_system->realpath($original_source)) !== FALSE) {
       $logger->notice('File %file (%realpath) could not be moved/copied because it does not exist.', array('%file' => $original_source, '%realpath' => $realpath));
     }
     else {
@@ -542,8 +544,8 @@ function file_unmanaged_prepare($source, &$destination = NULL, $replace = FILE_E
   }
 
   // Assert that the source and destination filenames are not the same.
-  $real_source = \Drupal::service('file_system')->realpath($source);
-  $real_destination = \Drupal::service('file_system')->realpath($destination);
+  $real_source = $file_system->realpath($source);
+  $real_destination = $file_system->realpath($destination);
   if ($source == $destination || ($real_source !== FALSE) && ($real_source == $real_destination)) {
     drupal_set_message(t('The specified file %file was not moved/copied because it would overwrite itself.', array('%file' => $source)), 'error');
     $logger->notice('File %file could not be moved/copied because it would overwrite itself.', array('%file' => $source));
@@ -643,8 +645,9 @@ function file_unmanaged_move($source, $destination = NULL, $replace = FILE_EXIST
   }
   // Attempt to resolve the URIs. This is necessary in certain configurations
   // (see above) and can also permit fast moves across local schemes.
-  $real_source = \Drupal::service('file_system')->realpath($source) ?: $source;
-  $real_destination = \Drupal::service('file_system')->realpath($destination) ?: $destination;
+  $file_system = \Drupal::service('file_system');
+  $real_source = $file_system->realpath($source) ?: $source;
+  $real_destination = $file_system->realpath($destination) ?: $destination;
   // Perform the move operation.
   if (!@rename($real_source, $real_destination)) {
     // Fall back to slow copy and unlink procedure. This is necessary for
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index d5a8ee9..354d537 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -425,19 +425,20 @@ function system_requirements($phase) {
     // Try to write the .htaccess files first, to prevent false alarms in case
     // (for example) the /tmp directory was wiped.
     file_ensure_htaccess();
+    $file_system = \Drupal::service('file_system');
     $htaccess_files['public://.htaccess'] = array(
       'title' => t('Public files directory'),
-      'directory' => \Drupal::service('file_system')->realpath('public://'),
+      'directory' => $file_system->realpath('public://'),
     );
     if (PrivateStream::basePath()) {
       $htaccess_files['private://.htaccess'] = array(
         'title' => t('Private files directory'),
-        'directory' => \Drupal::service('file_system')->realpath('private://'),
+        'directory' => $file_system->realpath('private://'),
       );
     }
     $htaccess_files['temporary://.htaccess'] = array(
       'title' => t('Temporary files directory'),
-      'directory' => \Drupal::service('file_system')->realpath('temporary://'),
+      'directory' => $file_system->realpath('temporary://'),
     );
     foreach ($htaccess_files as $htaccess_file => $info) {
       // Check for the string which was added to the recommended .htaccess file