Most phone owners come to realize that an old battery is a weak battery, one that gradually loses capacity. But it turns out that an old battery can also be a performance-killing battery, as evidenced by Apple’s recent revelation: Owing to an intentional software feature, some iPhones will run slower if they have older, failing batteries.

Fortunately, there’s a simple fix: Get a new battery. Previously, Apple charged $79 for such a swap, but effectively immediately, you can get a replacement battery from Apple for just $29. That’s for any iPhone 6 ($320.00 at or later. (A similar discount will be available outside the US — for example, the replacement cost will be lowered to £25 in the UK and AU$39 in Australia — and Apple says it will provide more details on its site soon.)

Do it. If your phone is more than a year old, it’s no doubt lost some of its capacity (and, apparently, some of its speed). This is a cheap and easy fix, one that will not only extend the life of your phone, but also make it feel kind of new again.

There are three ways to get this replacement done:

  • At an Apple Store
  • At an authorized Apple service center
  • By mail

I strongly recommend against that third option. For starters, it’ll leave you without your phone for at least a week — and if there’s any kind of problem, that could delay things even further.

To schedule an appointment locally, in a store or service center, head to Apple’s support page, click iPhone, then click Battery, Power & Charging. Now choose Battery replacement and then Bring in for Repair.

Next, you’ll need to sign in with your Apple ID and select the device you’re bringing in. From there you can find the nearest available location and choose a time.