diff --git a/core/core.services.yml b/core/core.services.yml
index d106942..7269288 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -1168,7 +1168,6 @@ services:
     alias: plugin.manager.element_info
   file.mime_type.mapper:
     class: Drupal\Core\File\MimeType\MimeTypeMapper
-    arguments: ['@module_handler']
   file.mime_type.guesser:
     class: Drupal\Core\File\MimeType\MimeTypeGuesser
     arguments: ['@stream_wrapper_manager']
diff --git a/core/lib/Drupal/Core/File/MimeType/MimeTypeMapper.php b/core/lib/Drupal/Core/File/MimeType/MimeTypeMapper.php
index 627b458..1f0299d 100644
--- a/core/lib/Drupal/Core/File/MimeType/MimeTypeMapper.php
+++ b/core/lib/Drupal/Core/File/MimeType/MimeTypeMapper.php
@@ -19,7 +19,7 @@ class MimeTypeMapper implements MimeTypeMapperInterface {
    * @var array
    *   Array of mimetypes correlated to the extensions that relate to them.
    */
-  protected $defaultMapping = array(
+  protected $mapping = array(
     'mimetypes' => array(
       0 => 'application/andrew-inset',
       1 => 'application/atom',
@@ -863,39 +863,9 @@ class MimeTypeMapper implements MimeTypeMapperInterface {
   );
 
   /**
-   * The MIME types mapping array after going through the module handler.
-   *
-   * @var array
-   */
-  protected $mapping;
-
-  /**
-   * The module handler.
-   *
-   * @var \Drupal\Core\Extension\ModuleHandlerInterface
-   */
-  protected $moduleHandler;
-
-  /**
-   * Constructs a new MimeTypeMapper.
-   *
-   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
-   *   The module handler.
-   */
-  public function __construct(ModuleHandlerInterface $module_handler) {
-    $this->moduleHandler = $module_handler;
-  }
-
-  /**
    * {@inheritdoc}
    */
   public function getMapping() {
-    if ($this->mapping === NULL) {
-      $mapping = $this->defaultMapping;
-      // Allow modules to alter the default mapping.
-      $this->moduleHandler->alter('file_mimetype_mapping', $mapping);
-      $this->mapping = $mapping;
-    }
     return $this->mapping;
   }
 
@@ -903,7 +873,6 @@ public function getMapping() {
    * {@inheritdoc}
    */
   public function getMimeTypes() {
-    // Fire alter hooks.
     list($mimetypes,) = $this->getMapping();
     return $mimetypes;
   }
@@ -912,7 +881,6 @@ public function getMimeTypes() {
    * {@inheritdoc}
    */
   public function getMimeTypeForExtension($extension) {
-    // Fire alter hooks.
     list($mimetypes, $extensions) = $this->getMapping();
     $extension = strtolower($extension);
     return isset($extensions[$extension]) ? $mimetypes[$extensions[$extension]] : NULL;