Notification on fixed build

Is there a way to send Slack message only when a build has been fixed, i.e. last build failed, current one succeed? For us there’s no need to receive a notification on every successful build so a solution to this would be greatly appreciated! I tried to mess around with DRONE_PREV_BUILD_STATUS in the message template but couldn’t get anything working.

Maybe there will be a way to do this in 0.9 or 1.0 release?