diff --git a/core/modules/system/lib/Drupal/system/FileController.php b/core/modules/system/lib/Drupal/system/FileController.php
index 064c555..349e373 100644
--- a/core/modules/system/lib/Drupal/system/FileController.php
+++ b/core/modules/system/lib/Drupal/system/FileController.php
@@ -48,7 +48,7 @@ public function __construct(ModuleHandler $module_handler) {
    * @see hook_file_download()
    */
   function fileDownload(Request $request, $scheme) {
-    $target = $request->request->get('file');
+    $target = $request->query->get('file');
     // Merge remaining path arguments into relative file path.
     $uri = $scheme . '://' . $target;