diff --git a/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php b/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
index 9a13acb..7d8c89b 100644
--- a/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/System/ThemeTest.php
@@ -259,4 +259,16 @@ function testInvalidTheme() {
     $this->assertText(t('This theme requires the base theme @base_theme to operate correctly.', array('@base_theme' => 'not_real_test_basetheme')), 'Invalid base theme check succeeded.');
     $this->assertText(t('This theme requires the theme engine @theme_engine to operate correctly.', array('@theme_engine' => 'not_real_engine')), 'Invalid theme engine check succeeded.');
   }
+
+  /**
+   * Ensure that the help text block is hidden on a 404 page error.
+   */
+  function testThemeSettingsNotFoundHelpText() {
+    // Ensure invalid theme settings form URLs return a proper 404.
+    $this->drupalGet('admin/appearance/settings/' . $this->randomName());
+    $this->assertResponse(404, 'The theme settings form URL for a non-existent theme could not be found.');
+    // Ensure help block does not display.
+    $help_block = $this->xpath("//div[@id='block-help']");
+    $this->assertFalse($help_block, 'The help block is not displayed.');
+  }
 }