More than 9 million cars have been recalled in the U.S. since Jan. 1 alone. Owners are being warned about dangerous Takata airbag inflators, the risk of fires in certain Hyundai and Kia models, faulty brake lights, and other serious safety issues.

But if any of those vehicles are for sale now—or enter the used-car market—shoppers may never know that the vehicle they’re considering needs important repair work done.

“Used-car shoppers are on their own,because dealers and private-party sellers aren’t required to make these needed repairs on used vehicles,” says Will Wallace, seniorpolicy analyst at Consumer Reports. “They don’t even have to inform potential buyers that a recall has been issued for the car they’re considering.”

That’s not the case for new cars, Wallace says.

“New-car dealers and rental car companies are specifically required by federal law to fix open defects before offering the car for sale to consumers,” he says.

In the market for a used car? Here’s what you can do to protect yourself.