diff --git a/admin_menu.module b/admin_menu.module
index 21bff9f..dc82450 100644
--- a/admin_menu.module
+++ b/admin_menu.module
@@ -5,6 +5,8 @@
  * Render an administrative menu as a dropdown menu at the top of the window.
  */
 
+define('ADMIN_MENU_CACHE_CID_PREFIX', 'admin_menu:');
+
 /**
  * Implements hook_help().
  */
@@ -154,7 +156,7 @@ function admin_menu_page_build(&$page) {
   if (strpos($_GET['q'], 'js/') === 0) {
     return;
   }
-  global $user, $language;
+  global $user;
   $path = drupal_get_path('module', 'admin_menu');
 
   $page['page_bottom']['admin_menu'] = array(
@@ -184,7 +186,7 @@ function admin_menu_page_build(&$page) {
 
   // If the client supports JavaScript and we have a cached menu for the current
   // user, only output the hash for the client-side HTTP cache callback URL.
-  $cid = 'admin_menu:' . $user->uid . ':' . session_id() . ':' . $language->language;
+  $cid = admin_menu_cache_get_cid();
   if (!$complete && !empty($_COOKIE['has_js']) && ($hash = admin_menu_cache_get($cid))) {
     $settings['hash'] = $hash;
     // The base path to use for cache requests depends on whether clean URLs
@@ -276,6 +278,18 @@ function admin_menu_js() {
 }
 
 /**
+ * Helper function to construct the cache id (cid).
+ */
+function admin_menu_cache_get_cid() {
+  global $user, $language;
+
+  $cid = ADMIN_MENU_CACHE_CID_PREFIX . $user->uid . ':' . session_id() . ':' . $language->language;
+  drupal_alter('admin_menu_cache_cid', $cid);
+
+  return $cid;
+}
+
+/**
  * Retrieve a client-side cache hash from cache.
  *
  * The hash cache is consulted more than once per request; we therefore cache
@@ -451,10 +465,8 @@ function admin_menu_session_count($timestamp = 0, $anonymous = TRUE) {
  *   page.
  */
 function admin_menu_output($complete = FALSE) {
-  global $user, $language;
-
   $cache_server_enabled = !$complete && variable_get('admin_menu_cache_server', TRUE);
-  $cid = 'admin_menu:' . $user->uid . ':' . session_id() . ':' . $language->language;
+  $cid = admin_menu_cache_get_cid();
 
   // Try to load and output administration menu from server-side cache.
   // @todo Duplicates the page cache? Page cache ID contains the hash that is
@@ -787,7 +799,7 @@ function admin_menu_flush_caches($uid = NULL) {
   }
   $was_flushed[$uid] = TRUE;
 
-  $cid = 'admin_menu:';
+  $cid = ADMIN_MENU_CACHE_CID_PREFIX;
   if (isset($uid)) {
     $cid .= $uid . ':';
   }