diff --git a/core/includes/theme.maintenance.inc b/core/includes/theme.maintenance.inc
index 6224854..9629ca2 100644
--- a/core/includes/theme.maintenance.inc
+++ b/core/includes/theme.maintenance.inc
@@ -82,7 +82,7 @@ function _drupal_maintenance_theme() {
   $theme = $custom_theme;
 
   // Find all our ancestor themes and put them in an array.
-  $base_themes = array();
+  $base_themes = [];
   $ancestor = $theme;
   while ($ancestor && isset($themes[$ancestor]->base_theme)) {
     $base_themes[] = $themes[$themes[$ancestor]->base_theme];
diff --git a/core/modules/system/src/Tests/Installer/InstallerThemeTest.php b/core/modules/system/src/Tests/Installer/InstallerThemeTest.php
index ffed969..04ebab9 100644
--- a/core/modules/system/src/Tests/Installer/InstallerThemeTest.php
+++ b/core/modules/system/src/Tests/Installer/InstallerThemeTest.php
@@ -9,7 +9,6 @@
 
 use Drupal\simpletest\KernelTestBase;
 
-
 /**
  * Tests themes and base themes are correctly loaded.
  *
@@ -19,13 +18,14 @@ class InstallerThemeTest extends KernelTestBase {
 
   /**
    * Tests themes and base themes are correctly loaded.
+   *
    * Regression test for: https://www.drupal.org/node/2614014
    */
   protected function testMaintenanceTheme() {
     $this->settingsSet('maintenance_theme', 'seven');
     // Get the maintenance theme loaded.
     drupal_maintenance_theme();
-    // Do we have an active
+    // Do we have an active theme?
     $this->assertTrue(\Drupal::theme()->hasActiveTheme());
 
     $active_theme = \Drupal::theme()->getActiveTheme();
@@ -36,7 +36,7 @@ protected function testMaintenanceTheme() {
     $this->assertTrue(count($base_themes) === 2);
     $this->assertEqual($base_theme_names[0], 'classy', 'Classy is the base theme of Seven');
     $this->assertEqual($base_theme_names[1], 'stable', 'Stable is the parent of Classy');
-    // Ensure base theme's have proper base themes and the right count.
+    // Ensure Classy has the correct base themes and amount of base themes.
     $classy_base_themes = $base_themes['classy']->getBaseThemes();
     $this->assertTrue(count($classy_base_themes) === 1);
     $this->assertTrue(isset($classy_base_themes['stable']));
diff --git a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
index fdbbd99..52bd25a 100644
--- a/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
+++ b/core/modules/system/src/Tests/Installer/StandardInstallerTest.php
@@ -44,7 +44,7 @@ protected function setUpSite() {
    * {@inheritdoc}
    */
   protected function curlExec($curl_options, $redirect = FALSE) {
-    // Ensure that we see the classy progress css on the page.
+    // Ensure that we see the classy progress CSS on the page.
     if (strpos($curl_options[CURLOPT_URL], '&id=1&op=do_nojs') !== FALSE) {
       $this->assertRaw('themes/classy/css/components/progress.css');
     }