diff --git a/src/Form/ConfigurationForm.php b/src/Form/ConfigurationForm.php
index 8df5034..16ed24a 100644
--- a/src/Form/ConfigurationForm.php
+++ b/src/Form/ConfigurationForm.php
@@ -25,6 +25,13 @@ class ConfigurationForm extends ConfigFormBase {
    */
   protected $manifest;
 
+  /**
+   * The system file config.
+   *
+   * @var \Drupal\Core\Config\ImmutableConfig
+   */
+  protected $configSystemFile;
+
   /**
    * Constructs a \Drupal\system\ConfigFormBase object.
    *
@@ -35,6 +42,7 @@ class ConfigurationForm extends ConfigFormBase {
     parent::__construct($config_factory);
 
     $this->manifest = $manifest;
+    $this->configSystemFile = $config_factory->get('system.file');
 
   }
 
@@ -74,8 +82,8 @@ class ConfigurationForm extends ConfigFormBase {
     if (substr($files_path, 0, strlen($host)) == $host) {
       $files_path = str_replace($host, '', $files_path);
     }
-    $wrapper = \Drupal::service('stream_wrapper_manager')->getViaScheme(\Drupal::config('system.file')->get('default_scheme'));
-    $realpath = \Drupal::service('file_system')->realpath(\Drupal::config('system.file')->get('default_scheme') . "://");
+    $wrapper = \Drupal::service('stream_wrapper_manager')->getViaScheme($this->configSystemFile->get('default_scheme'));
+    $realpath = \Drupal::service('file_system')->realpath($this->configSystemFile->get('default_scheme') . "://");
 
     $config = $this->config('pwa.config');
 
@@ -401,7 +409,7 @@ class ConfigurationForm extends ConfigFormBase {
       $file_usage->add($file, 'PWA', 'PWA', $this->currentUser()->id());
 
       // Save new image.
-      $wrapper = \Drupal::service('stream_wrapper_manager')->getViaScheme(\Drupal::config('system.file')->get('default_scheme'));
+      $wrapper = \Drupal::service('stream_wrapper_manager')->getViaScheme($this->configSystemFile->get('default_scheme'));
       $files_path = '/' . $wrapper->basePath() . '/pwa/';
       $file_uri = $files_path . $file->getFilename();