diff --git a/core/modules/language/language.admin.inc b/core/modules/language/language.admin.inc
index 75661ce..0edc193 100644
--- a/core/modules/language/language.admin.inc
+++ b/core/modules/language/language.admin.inc
@@ -361,8 +361,10 @@ function language_negotiation_configure_form() {
     '#language_negotiation_info' => language_negotiation_info(),
   );
   $form['#language_types'] = array();
-  foreach ($form['#language_types_info'] as $type => $value) {
-    if (!empty($value['name'])) {
+  foreach ($form['#language_types_info'] as $type => $info) {
+    // Show locked language types only if they do not already define a fixed
+    // configuration. In the latter case they always are configurable.
+    if (empty($info['locked']) || !isset($info['fixed'])) {
       $form['#language_types'][] = $type;
     }
   }
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index 8e75500..9ae1109 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -620,14 +620,17 @@ function language_language_types_info() {
     LANGUAGE_TYPE_INTERFACE => array(
       'name' => t('User interface text'),
       'description' => t('Order of language detection methods for user interface text. If a translation of user interface text is available in the detected language, it will be displayed.'),
+      'locked' => TRUE,
     ),
     LANGUAGE_TYPE_CONTENT => array(
       'name' => t('Content'),
       'description' => t('Order of language detection methods for content. If a version of content is available in the detected language, it will be displayed.'),
       'fixed' => array(LANGUAGE_NEGOTIATION_INTERFACE),
+      'locked' => TRUE,
     ),
     LANGUAGE_TYPE_URL => array(
       'fixed' => array(LANGUAGE_NEGOTIATION_URL, LANGUAGE_NEGOTIATION_URL_FALLBACK),
+      'locked' => TRUE,
     ),
   );
 }
diff --git a/core/modules/translation_entity/translation_entity.module b/core/modules/translation_entity/translation_entity.module
index 83973f4..f38ea74 100644
--- a/core/modules/translation_entity/translation_entity.module
+++ b/core/modules/translation_entity/translation_entity.module
@@ -60,6 +60,14 @@ function translation_entity_module_implements_alter(&$implementations, $hook) {
 }
 
 /**
+ * Implements hook_language_type_info_alter().
+ */
+function translation_entity_language_types_info_alter(array &$language_types) {
+  // Make content language negotiation customizable by unlocking it.
+  unset($language_types[LANGUAGE_TYPE_CONTENT]['locked']);
+}
+
+/**
  * Implements hook_entity_info_alter().
  */
 function translation_entity_entity_info_alter(array &$entity_info) {