--- subscriptions.module	2013-03-03 08:06:54.000000000 -0800
+++ subscriptions.module.new	2013-03-11 11:30:34.086478988 -0700
@@ -331,7 +331,7 @@
   $query
     ->fields('s', array('send_interval', 'author_uid', 'send_updates', 'send_comments'))
     ->condition('s.recipient_uid', $rids, 'IN');
-  db_insert('subscriptions')
+  db_insert('subscriptions', array('return' => Database::RETURN_NULL))
     ->from($query)
     ->execute();
 }