diff --git a/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorTest.php b/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorTest.php
index bdd651d..c51c95b 100644
--- a/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorTest.php
+++ b/core/modules/ckeditor/lib/Drupal/ckeditor/Tests/CKEditorTest.php
@@ -309,6 +309,27 @@ function testStylesComboGetConfig() {
     $this->assertIdentical($expected, $stylescombo_plugin->getConfig($editor), '"StylesCombo" plugin configuration built correctly for customized toolbar.');
   }
 
+  /**
+   * Tests language list availability in CKEditor.
+   */
+  function testLanguages() {
+    // Get CKEditor supported language codes and spot-check.
+    $this->enableModules(array('language'));
+    config_install_default_config('module', 'language');
+    $langcodes = $this->ckeditor->getLangcodes();
+
+    // Language codes transformed with browser mappings.
+    $this->assertTrue($langcodes['pt-pt'] == 'pt', '"pt" properly resolved');
+    $this->assertTrue($langcodes['zh-hans'] == 'zh-cn', '"zh-hans" properly resolved');
+
+    // Language code both in Drupal and CKEditor.
+    $this->assertTrue($langcodes['gl'] == 'gl', '"gl" properly resolved');
+
+    // Language codes only in CKEditor.
+    $this->assertTrue($langcodes['en-au'] == 'en-au', '"en-au" properly resolved');
+    $this->assertTrue($langcodes['sr-latn'] == 'sr-latn', '"sr-latn" properly resolved');
+  }
+
   protected function getDefaultInternalConfig() {
     return array(
       'customConfig' => '',
diff --git a/core/modules/language/config/language.mappings.yml b/core/modules/language/config/language.mappings.yml
index ede8c9e..f7fc321 100644
--- a/core/modules/language/config/language.mappings.yml
+++ b/core/modules/language/config/language.mappings.yml
@@ -1,8 +1,8 @@
 # Browsers use different language codes to refer to the same languages,
 # these defaults handles the most common cases.
 no: 'nb' # Norwegian
-pt-pt: 'pt' # Portuguese
-zh: 'zh-hans'
+pt: 'pt-pt' # Portuguese
+zh: 'zh-hans' # Default Chinese to simplified script
 zh-tw: 'zh-hant' # Taiwan Chinese in traditional script
 zh-hk: 'zh-hant' # Hong Kong Chinese in traditional script
 zh-mo: 'zh-hant' # Macao Chinese in traditional script