diff --git a/core/modules/taxonomy/src/Tests/RssTest.php b/core/modules/taxonomy/src/Tests/RssTest.php
index fb3607a..dd8b382 100644
--- a/core/modules/taxonomy/src/Tests/RssTest.php
+++ b/core/modules/taxonomy/src/Tests/RssTest.php
@@ -104,7 +104,7 @@ function testTaxonomyRss() {
     // Post an article.
     $edit = array();
     $edit['title[0][value]'] = $this->randomMachineName();
-    $edit[$this->field_name . '[]'] = $term1->id();
+    $edit[$this->fieldName . '[]'] = $term1->id();
     $edit['promote[value]'] = TRUE;
     $this->drupalPostForm('node/add/article', $edit, t('Save and publish'));