Apple will allow iPhone users to switch off the performance reductions that the company has introduced in the last year to counteract the effects of ageing batteries, Tim Cook has said.

However, the Apple CEO advised users not to do so, warning that it could result in unexpected restarts of their smartphones.

Cook’s comments came in a Wednesday ABC interview that largely dealt with Apple’s plans to pay $38 billion in taxes to repatriate hundreds of billions of overseas dollars—a move it attributes to the recent tax overhaul—and to recruit 20,000 workers over the next five years.

The interview also delved into the battery controversy, which hit last month when it emerged that Apple aapl was artificially degrading the performance of certain older iPhone models. The company is adamant that this is not a ploy to get people to buy newer models, but a tactic designed to stop devices from unexpectedly restarting, due to the limitations brought on by battery age.

On Wednesday, Cook reiterated what Apple already said last month: that early this year it would introduce a feature that lets users check on the health of their battery, so they can better understand why Apple is slowing down their phone. That feature will arrive in a developer version of iOS next month, he said, before rolling out to the public.

However, he went further by announcing that people would be able to bypass the artificial performance degradation.

“We will tell somebody saying we’re slightly reducing, or we’re reducing your performance by some amount in order to not have an unexpected restart, and if you don’t want it, you can turn it off,” Cook said. “Now, we don’t recommend it because we think that people’s iPhones are very important to them and you never can tell when something is so urgent [that an unexpected restart could have a negative effect].”

As part of its attempt to minimize the backlash against its battery strategy, Apple has also cut the price of battery replacements from $79 to $29.

The affected models include the iPhones 6, 6 Plus, 6s, 6s Plus, and SE.