Mini is recalling about 35,000 cars in the US and Canada because they don't meet side-impact crash-test requirements.
The recall includes certain Cooper and Cooper S Hardtop two-door cars from 2014 and 2015, as well as the 2015 John Cooper Works Hardtop two-door.
The company owned by BMW says that if crash-test requirements aren't met, rear-seat passengers could have a higher risk of injury.
Dealers will install more energy absorption material between the rear interior side panels and the body starting September 12.
The company says in documents filed with US safety regulators that it knows of no crashes or injuries from the problem.
The recall includes 30,456 cars in the US and another 4,130 in Canada.