diff -u b/core/includes/install.core.inc b/core/includes/install.core.inc
--- b/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -1860,9 +1860,8 @@
 
   $readable = FALSE;
   $writable = FALSE;
-  // @todo: Make this configurable.
-  $files_directory = conf_path() . '/files';
-  $translations_directory = conf_path() . '/files/translations';
+  $files_directory = variable_get('file_public_path', conf_path() . '/files');
+  $translations_directory = variable_get('locale_translate_file_directory', conf_path() . '/files/translations');
   $translations_directory_exists = FALSE;
   $online = FALSE;
   $server_available = FALSE;
@@ -1872,8 +1871,9 @@
 
   $readable = FALSE;
   $writable = FALSE;
-  $files_directory = variable_get('file_public_path', conf_path() . '/files');
-  $translations_directory = variable_get('locale_translate_file_directory', conf_path() . '/files/translations');
+  // @todo: Make this configurable.
+  $files_directory = conf_path() . '/files';
+  $translations_directory = conf_path() . '/files/translations';
   $translations_directory_exists = FALSE;
   $online = FALSE;
   $server_available = FALSE;
diff -u b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
--- b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
+++ b/core/lib/Drupal/Component/PhpStorage/PhpStorageFactory.php
@@ -49,7 +49,7 @@
       $configuration['bin'] = $name;
     }
     if (!isset($configuration['directory'])) {
-      $path = isset($conf['system.file.path.public']) ? $conf['system.file.path.public'] : conf_path() . '/files';
+      $path = isset($conf['system.file']['path.public']) ? $conf['system.file']['path.public'] : conf_path() . '/files';
       $configuration['directory'] = DRUPAL_ROOT . "/$path/php";
     }
     return new $class($configuration);
diff -u b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
--- b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
+++ b/core/lib/Drupal/Core/StreamWrapper/PublicStream.php
@@ -19,8 +19,7 @@
    * Implements Drupal\Core\StreamWrapper\LocalStream::getDirectoryPath()
    */
   public function getDirectoryPath() {
-    //return config('system.file')->get('path.public');
-    return conf_path() . '/files';
+    return config('system.file')->get('path.public');
   }
 
   /**
diff -u b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
--- b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/UnitTestBase.php
@@ -56,7 +56,9 @@
     $conf = array();
     drupal_static_reset();
 
-    $conf['system.file.path.public'] = $this->public_files_directory;
+    $conf['system.file'] = array(
+      'path.public' => $this->public_files_directory,
+    );
 
     // Change the database prefix.
     // All static variables need to be reset before the database prefix is
diff -u b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
--- b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -797,7 +797,7 @@
     );
     foreach ($variable_groups as $config_base => $variables) {
       foreach ($variables as $name => $value) {
-      $GLOBALS['conf'][$config_base][$name] = $value;
+        $GLOBALS['conf'][$config_base][$name] = $value;
       }
     }
     // Execute the non-interactive installer.
diff -u b/core/modules/system/system.install b/core/modules/system/system.install
--- b/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -531,7 +531,7 @@
   state()->set('system.cron_key', $cron_key);
 
   // Populate default for public file path.
-  if (empty($GLOBALS['system.file.path.public'])) {
+  if (empty($GLOBALS['system.file']['path.public'])) {
     config('system.file')
       ->set('path.public', conf_path(TRUE, TRUE) . '/files')
       ->save();