Notification email for Status going Ready

I'm looking to send a notification email to the record owner when the status of the record goes ready. Currently this is done when the predecessor record in the workflow is marked complete: the task status is automatically changed from pending to ready for the desired task as a result of the predecessor being marked complete.

The issue with my notification logic is that it is set to fire when the record is modified. Unfortunately, the user is not actually modifying the record that is being changed to ready, they are only modifying the predecessor record and thus my notification is not functioning correctly.

Any suggestion on how to get around this?