diff --git a/cron.php b/cron.php
index e40dc2d9be8..cc6f4bffca4 100644
--- a/cron.php
+++ b/cron.php
@@ -10,4 +10,7 @@ include_once './includes/bootstrap.inc';
 drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);
 if (isset($_GET['cron_key']) && variable_get('cron_key', 'drupal') == $_GET['cron_key']) {
   drupal_cron_run();
-}
\ No newline at end of file
+}
+else {
+  watchdog('cron', 'Cron did not run because an invalid key used.', array(), WATCHDOG_NOTICE);
+}