diff --git a/modules/system/system.module b/modules/system/system.module
index ccfce53..3e88369 100644
--- a/modules/system/system.module
+++ b/modules/system/system.module
@@ -2258,6 +2258,9 @@ function system_cron() {
     ))
     ->condition('expire', REQUEST_TIME, '<')
     ->execute();
+
+  // Clean up expired sessions (for systems that have automatic session garbage collection off in php.ini)
+  _drupal_session_garbage_collection(ini_get('session.gc_maxlifetime'));
 }
 
 /**