diff --git a/core/modules/system/language.api.php b/core/modules/system/language.api.php
index 7e7d6b9..b3efba2 100644
--- a/core/modules/system/language.api.php
+++ b/core/modules/system/language.api.php
@@ -52,6 +52,9 @@ function hook_language_switch_links_alter(array &$links, $type, $path) {
  *     present and locked is TRUE then LANGUAGE_NEGOTIATION_INTERFACE will be
  *     used.
  *
+ *  @todo Rename the 'fixed' key to something more meaningful, for instance
+ *     'negotiation settings'.
+ *
  * @see hook_language_types_info_alter()
  * @ingroup language_negotiation
  */