Apple, the American multi-national technology company, has acknowledged it has taken action that slows the performance of its older iPhones.

After Primate Labs, which makes an application that measures the speed of iPhone processors, disclosed data Monday that seemingly showed the iPhone 6 and iPhone 7 models perform slower as they aged, Apple addressed the claims two days later.

Apple said it released software last year that makes those models operate more slowly to countervail problems with their aging lithium ion batteries, which can sometimes cause operational problems or cause phones to unexpectedly shut down.

The technology giant said the reason for the updated software was to provide better power management capabilities, which also slows down the phones, to prevent them from shutting down.

One solution to a slower, older iPhone would be to buy a new battery instead of a new phone. Apple charges $79 to replace the battery if the phone is no longer covered by a warranty. Owners can also purchase a kit to replace the battery. But the company has long been criticized by repair advocates for making the batteries difficult for users to replace on their own.