Knowing when to walk away from a job is challenging.

At some point in most roles, we notice we’re no longer excited to clock in and start a new project, or that our manager drives us crazy. But when do these things become dealbreakers — and should they really be the reason you leave?

HR data platform Peakon examined its database of more than 34 million worker survey responses, which included information from more than 36,000 departing employees, to see if they could predict which employees are likely to resign, based on their replies, and when they would do so.

Most workers, Peakon learned, begin showing signs they’re dissatisfied and itching to move on nine months before they hand in their notice. From this point forward, employee engagement, loyalty and happiness all begin to wane until an employee ultimately leaves.

But how do you decide when you’re not just frustrated and that it’s actually time to walk away? Peakon found there are four key signals — here’s how to know when they’ve become a problem for you: