As our work hours stretch longer—up 4% from a regular day just four years ago—more than half of us now say our jobs have become too busy, according to a recent Staples survey of U.S. employees.

And it can get worse if your company is going through layoffs or churn. Suddenly, your boss unloads the extra job duties of an exiting employee onto you. Now you’ve got two jobs, but you’re still getting paid for one.

“When churn happens, they may find a replacement,” says career strategist and creator of Careerealism.com J.T. O’Donnell, but “they are not going to be able to find the right person immediately.”

That can leave you picking up the slack for the lack of quality bodies in the workplace. But if you don’t want the new tasks combined with your old duties to become a permanent position, you’ll have to tread lightly, since you also want to prove you’re a team player who can handle the trust. “It’s an opportunity to show your employer you have the capacity to do more,” says O’Donnell.

It’s never an easy balance to strike, but here’s how to walk that line if your boss asks you to do two jobs for the price of one, while making sure it doesn’t stay that way.

Treat the initial conversation like a job interview

When your boss first calls you into the office to explain why you need to take on the extra roles, your initial instinct will be to say yes to everything. Don’t.

“Take it all in since that’s a big piece of news,” says executive coach Julie Cohen. However, she says, “you don’t need to know what to say exactly then and there.”

Cohen likens the encounter to a job interview. When you’re discussing any new role with a company, you don’t immediately say yes. Instead, weigh the decision, making sure it’s the right fit for you, because in many ways, you are getting a new job.

Have your boss outline every new job duty you’ll take on. Then say you’ll need some time to process all the new information and that you will respond the following workday. This will give you time to understand whether or not you actually have the capacity to pull it off, decide which tasks you can or can’t take on, and set up clear timelines for the work.

Come up with a plan

Now that you have given yourself some time to weigh the decision, figure out how you can accomplish it. You can probably handle some of the new tasks without a problem, but others may require new skills. Set up a game plan before talking to your boss again.

“You want to show initiative,” says Cohen. Clearly state that “A and B are in my wheelhouse, but if you want me to focus on C and D, I’m going to need support and training.”

Also look for ways in which the new role will bolster your career. Some of the new tasks may be senior to your level. If so, embrace them and show your boss that you can be trusted to take them on. But if some of those tasks are below your pay grade, develop a strategy to pass along the more rudimentary responsibilities to junior staff or interns. You’re not dumping work. Instead, says Cohen, “you’re showing leadership competencies and creating realistic expectations and opportunities for yourself.”

Set a clear timeline

When you meet with your boss again to outline your plan, don’t shy away from asking when your company hopes to hire a replacement. It gives you the opening to continue checking in on the status of a new hire, but it also sets the expectation that you’re not planning on doing two jobs forever.

“It’s quite a matter-of-fact question: If Mary left, alright, now what’s the strategy?” says O’Donnell. “Managers are very business driven, so it’s actually a sign you understand the business.”

If months go by and there’s still no new body, volunteer to take on the hiring process since you now know what to look for in your replacement. But watch out if your boss turns your offer down—it could mean he or she has been lying to you about their intentions. “Who is going to say no for you doing the recruiting?” asks O’Donnell. “If they do, you’re being taken advantage of.”

Schedule regular check-ins

As you and your boss discuss and tweak your plan of action, set up a time every two weeks or once a month to check in. This will give you a chance to showcase what you’re doing for the company, and it naturally opens the door to hear about how the hiring process is going.

If you’ve really begun to enjoy some of your new roles, then talk with your boss about how you’re performing and why you might want to switch titles. Or if the search for a new hire drags on, you’ve already demonstrated your value through the check-ins, which could help you negotiate a pay bump, extra vacation, or perks.

But if your boss does not agree to regular check-ins or always avoids them, then it’s possible he or she has no plans to find a replacement. At that point, it’s time to have a tough conversation with your manager.

“You have to sit down and nip that in the bud,” says O’Donnell. “You’re certainly not going anywhere doing two people’s jobs.”