diff --git a/core/modules/file/src/Tests/FileManagedFileElementTest.php b/core/modules/file/src/Tests/FileManagedFileElementTest.php
index 9074166..9953217 100644
--- a/core/modules/file/src/Tests/FileManagedFileElementTest.php
+++ b/core/modules/file/src/Tests/FileManagedFileElementTest.php
@@ -41,10 +41,10 @@ function testManagedFile() {
           // was not saved.
           $last_fid_prior = $this->getLastFileId();
           $edit = [
-            'files[' . $input_base_name . ']' => drupal_realpath($test_file->getFileUri()),
+            $file_field_name => drupal_realpath($test_file->getFileUri()),
             'form_token' => 'invalid token',
           ];
-          $this->drupalPost($path, $edit, t('Save'));
+          $this->drupalPostForm($path, $edit, t('Save'));
           $this->assertText('The form has become outdated. Copy any unsaved work in the form below');
           $last_fid = $this->getLastFileId();
           $this->assertEqual($last_fid_prior, $last_fid, 'File was not saved when uploaded with an invalid form token.');