diff --git a/core/includes/language.inc b/core/includes/language.inc
index 66e1363..72eebef 100644
--- a/core/includes/language.inc
+++ b/core/includes/language.inc
@@ -208,36 +208,40 @@ function language_types_set(array $customized_language_types) {
   // information.
   drupal_static_reset('language_types_info');
   drupal_static_reset('language_negotiation_info');
-  $config_values = array();
+  $customized = array();
 
   $negotiation_info = language_negotiation_info();
   $language_types_info = language_types_info();
   foreach ($language_types_info as $type => $info) {
     $customized[$type] = in_array($type, $customized_language_types);
-    // Check if the language is locked. The configuration of a locked language
-    // type cannot be changed using the UI.
+    // Check if the language is unlocked. Only unlocked language types can have
+    // their customized setting changed using the UI.
     if (empty($info['locked'])) {
-      // The configuration of unlocked languages set using the UI. Save this
-      // data to the $customized array (stored in configuration).
       if ($customized[$type] && empty($info['fixed'])) {
-        // If the language is not configurable and there is no default language
-        // negotiation setting then provide one.
+        // If its customized (table is shown) and it has no default settings we
+        // give it some sane defaults that come from the language negotiation
+        // interface.
         $method_weights = array(LANGUAGE_NEGOTIATION_INTERFACE);
         $method_weights = array_flip($method_weights);
         language_negotiation_set($type, $method_weights);
       }
     }
     else {
-      // Locked languages don't allow changing their configurable state.
+      // The language type is locked. Locked language types do not get a
+      // customize checkbox in the UI.
 
       // Default language negotiation is stored in $info['fixed']. Locked
-      // language types with a default value are not configurable. Locked
-      // language types without a default value are always configurable.
+      // language types with a default value do not get a table. Locked
+      // language types without a default value always get a table.
+      // If default settings is empty, then customized is true, and the table
+      // should be shown.
       $customized[$type] = empty($info['fixed']);
 
       if (!empty($info['fixed'])) {
-        // Set the language negotiation for non configurable types to use the
-        // default settings stored in $info['fixed'].
+        // Language type is locked and has default settings and will never seen
+        // in the UI, for example URL language type.
+
+        // The language type has default settings, stored in $info['fixed'].
         $method_weights = array();
         foreach ($info['fixed'] as $weight => $method_id) {
           if (isset($negotiation_info[$method_id])) {
diff --git a/core/modules/language/language.admin.inc b/core/modules/language/language.admin.inc
index b5d3560..c4b5d8d 100644
--- a/core/modules/language/language.admin.inc
+++ b/core/modules/language/language.admin.inc
@@ -561,18 +561,18 @@ function theme_language_negotiation_configure_form($variables) {
 function language_negotiation_configure_form_submit($form, &$form_state) {
   $configurable_types = $form['#language_types'];
 
-  $configurable = config('system.language.types')->get('configurable');
-  $config_values = array();
+  $customized_types = config('system.language.types')->get('configurable');
+  $customized = array();
   $method_weights_type = array();
 
   foreach ($configurable_types as $type) {
-    $config_values[$type] = in_array($type, $configurable);
+    $customized[$type] = in_array($type, $customized_types);
     $method_weights = array();
     $enabled_methods = $form_state['values'][$type]['enabled'];
     $enabled_methods[LANGUAGE_NEGOTIATION_SELECTED] = TRUE;
     $method_weights_input = $form_state['values'][$type]['weight'];
     if (isset($form_state['values'][$type]['configurable'])) {
-      $config_values[$type] = !empty($form_state['values'][$type]['configurable']);
+      $customized[$type] = !empty($form_state['values'][$type]['configurable']);
     }
 
     foreach ($method_weights_input as $method_id => $weight) {
@@ -587,7 +587,7 @@ function language_negotiation_configure_form_submit($form, &$form_state) {
 
   // Update non-configurable language types and the related language negotiation
   // configuration.
-  language_types_set(array_keys(array_filter($config_values)));
+  language_types_set(array_keys(array_filter($customized)));
 
   // Update the language negotiations after setting the configurability.
   foreach ($method_weights_type as $type => $method_weights) {
@@ -599,7 +599,7 @@ function language_negotiation_configure_form_submit($form, &$form_state) {
   if (module_exists('block')) {
     // If there is an active language switcher for a language type that has been
     // made not configurable, deactivate it first.
-    $non_configurable = array_keys(array_diff($config_values, array_filter($config_values)));
+    $non_configurable = array_keys(array_diff($customized, array_filter($customized)));
     _language_disable_language_switcher($non_configurable);
     Drupal::service('plugin.manager.block')->clearCachedDefinitions();
   }
@@ -627,10 +627,8 @@ function language_negotiation_configure_browser_form($form, &$form_state) {
   // the list of existing and then predefined languages.
   if (empty($existing_languages)) {
     $language_options = language_admin_predefined_list();
-    $default = key($language_options);
   }
   else {
-    $default = key($existing_languages);
     $language_options = array(
       t('Existing languages') => $existing_languages,
       t('Languages not yet added') => language_admin_predefined_list()
diff --git a/core/modules/language/language.install b/core/modules/language/language.install
index 9f74b97..b7b3c77 100644
--- a/core/modules/language/language.install
+++ b/core/modules/language/language.install
@@ -18,6 +18,7 @@ function language_install() {
   // Enable URL language detection for each configurable language type.
   require_once DRUPAL_ROOT . '/core/includes/language.inc';
   foreach (language_types_get_configurable() as $type) {
+    module_load_include('inc', 'language', 'language.negotiation');
     language_negotiation_set($type, array(LANGUAGE_NEGOTIATION_URL => 0));
   }
 }