diff --git a/core/modules/translation_entity/translation_entity.admin.js b/core/modules/translation_entity/translation_entity.admin.js
index d9c132a..fd89735 100644
--- a/core/modules/translation_entity/translation_entity.admin.js
+++ b/core/modules/translation_entity/translation_entity.admin.js
@@ -105,65 +105,72 @@ Drupal.behaviors.translationEntity = {
 
 /**
  * Removes unusable locked languages when not showing language selector.
+ *
  * This behavior gets attached on the relevant entity edition form and
  * the translation entity summary form.
  */
- Drupal.behaviors.lockedSelector = {
-   attach: function (context) {
-     var $context = $(context);
-
-     // Declare the function in scope and reuse it later.
-     var filterAvailableLanguages = function ($languageSelector, $checkbox, $translatable) {
-       // Get the list of all languages and unlocked languages based on the original
-       // language selector options.
-       var $originalOptions = $languageSelector.data('originalOptions');
-       if (typeof($originalOptions) !== 'undefined') {
-         var $unlockedOptions = $originalOptions.filter(function (index) { return !/^- .* -$/.test(this.text); });
-         if ($translatable.size() == 0 || $translatable.is(':checked')) {
-           if ($checkbox.is(':checked')) {
-             $languageSelector.html($originalOptions);
-             $checkbox.siblings('.description').css('opacity', 0);
-           }
-           else {
-             $languageSelector.html($unlockedOptions);
-             $checkbox.siblings('.description').css('opacity', 1);
-           }
-         }
-         else {
-           $languageSelector.html($originalOptions);
-           $checkbox.siblings('.description').css('opacity', 0);
-         }
-       };
-     };
-
-     var processSelectors = function ($container) {
-       if ($container.size()) {
-         // Store the data about original options in the language selector
-         // Do it only once to avoid losing options
-         $container.once('locked-selector-options').each(function (index, element) {
-           $('.langcode-select', element).data('originalOptions', $('option', $('.langcode-select', element)));
-         });
-         $container.each(function (index, element) {
-           var $languageSelector = $('.langcode-select', element);
-           var $checkbox = $('.language-show-checkbox', element);
-
-           // Execute the function at the beginning and whenever the relevant checkbox
-           // is clicked
-           $checkbox.on('click', function (e) {
-             filterAvailableLanguages($languageSelector, $checkbox, $translatable);
-           });
-           filterAvailableLanguages($languageSelector, $checkbox, $translatable);
-         });
-       };
-     };
-
-     // Determine the kind of form we are dealing with
-     var $container = $('.bundle-settings .operations, .details-wrapper', context);
-     var $translatable = $('.translation-enabled-checkbox').once('locked-selector-options').on('click', function (e) {
-       processSelectors($container);
-     });
-     processSelectors($container);
-   }
- };
+Drupal.behaviors.lockedSelector = {
+  attach: function (context) {
+    var $context = $(context);
+
+    // A custom message for the changed language options.
+    Drupal.theme.tableOptionsChangedWarning = function () {
+     return '<div class="messages warning">' + Drupal.t('You default language has been changed. You need to show the language selector to use a locked language.') + '</div>';
+    };
+
+    // Declare the function in scope and reuse it later.
+    var filterAvailableLanguages = function ($languageSelector, $checkbox, $translatable) {
+      // Get the list of all languages and unlocked languages based on the original
+      // language selector options.
+      var $originalOptions = $languageSelector.data('originalOptions');
+      if (typeof($originalOptions) !== 'undefined') {
+        var $unlockedOptions = $originalOptions.filter(function (index) { return !/^- .* -$/.test(this.text); });
+        if ($translatable.size() == 0 || $translatable.is(':checked')) {
+          if ($checkbox.is(':checked')) {
+            $languageSelector.html($originalOptions).siblings('.description').find('.hidden-languages').hide();
+          }
+          else {
+            // Warn the user if a locked language was selected.
+            if (/^- .* -$/.test($languageSelector.find(':selected').text())) {
+            $(Drupal.theme('tableOptionsChangedWarning')).insertBefore($('.form-type-vertical-tabs')).hide().fadeIn('slow');
+            };
+            $languageSelector.html($unlockedOptions).siblings('.description').find('.hidden-languages').show();
+          }
+        }
+        else {
+          $languageSelector.html($originalOptions).siblings('.description').find('.hidden-languages').hide();
+        }
+      };
+    };
+
+    var processSelectors = function ($container) {
+      if ($container.size()) {
+        // Store the data about original options in the language selector
+        // Do it only once to avoid losing options
+        $container.once('locked-selector-options').each(function (index, element) {
+          $('.langcode-select', element).data('originalOptions', $('option', $('.langcode-select', element)));
+        });
+        $container.each(function (index, element) {
+          var $languageSelector = $('.langcode-select', element);
+          var $checkbox = $('.language-show-checkbox', element);
+
+          // Execute the function at the beginning and whenever the relevant checkbox
+          // is clicked
+          $checkbox.on('click', function (e) {
+            filterAvailableLanguages($languageSelector, $checkbox, $translatable);
+          });
+          filterAvailableLanguages($languageSelector, $checkbox, $translatable);
+        });
+      };
+    };
+
+    // Determine the kind of form we are dealing with
+    var $container = $('.bundle-settings .operations, .details-wrapper', context);
+    var $translatable = $('.translation-enabled-checkbox').once('locked-selector-options').on('click', function (e) {
+      processSelectors($container);
+    });
+    processSelectors($container);
+  }
+};
 
 })(jQuery);
diff --git a/core/modules/translation_entity/translation_entity.module b/core/modules/translation_entity/translation_entity.module
index a26bb02..d903e10 100644
--- a/core/modules/translation_entity/translation_entity.module
+++ b/core/modules/translation_entity/translation_entity.module
@@ -921,15 +921,17 @@ function translation_entity_language_configuration_element_process(array $elemen
     $form_state['translation_entity']['key'] = $element['#name'];
     $context = $form_state['language'][$element['#name']];
     $element['#attached']['library'][] = array('translation_entity', 'drupal.translation_entity.admin');
-    // Description only visible if the bundle is translatable and the
-    // language selector is shown
-    $element['language_show']['#description'] = t('Some default language options are hidden if the language selector is not shown and translation is enabled.');
-
-    // Adds CSS classes for easier JS selection
-    $element['language_show'] = array_merge_recursive($element['language_show'], array('#attributes' => array(
-      'class' => array('language-show-checkbox')
-    )));
+
+    if (isset($element['langcode'])) {
+      // Adds CSS classes for easier JS selection
+      $element['language_show'] = array_merge_recursive($element['language_show'], array('#attributes' => array(
+        'class' => array('language-show-checkbox')
+      )));
+    }
     if (isset($element['langcode'])) {
+      // Description only visible if the bundle is translatable and the
+      // language selector is shown
+      $element['langcode']['#description'] .= '<span class="hidden-languages"> ' . t('Some default language options are hidden if the language selector is not shown and translation is enabled.') . '</span>';
       $element['langcode'] = array_merge_recursive($element['langcode'], array('#attributes' => array(
         'class' => array('langcode-select')
       )));