user warning: BIGINT UNSIGNED value is out of range in notifications_event table

Hi all,

I am using Notifications 6.x-2.3 for content subscription and it is working nicely, but when I create more than 4 blogs continuously then I am getting this problem after blog saved :

user warning: BIGINT UNSIGNED value is out of range in '(`db_name`.`notifications_event`.`counter` - 88)' query: UPDATE notifications_event SET counter = counter - 88 WHERE eid = 9 in /sites/all/modules/notifications/notifications.cron.inc on line 387

Although mails are sending but some users getting double mail.

Any help is much appreciated.