With Apple’s newly discounted battery replacement program in full swing, iPhone owners are heading to Apple stores in droves in hopes of speeding up their older devices. Unfortunately, iPhone 6 Plus owners are being forced to wait thanks to severely limited supply.

According to MacRumors, citing an internal document distributed to Apple stores and authorized service providers, iPhone 6 Plus battery replacements won’t be available until March at the earliest, forcing users to wait a few months before their phone can get serviced. Worst case scenario, supply could potentially be limited until early April.

The good news is many of Apple’s other devices, including the iPhone 7, iPhone 7 Plus, and iPhone SE, shouldn’t be hit with any delays. Owners of the iPhone 6, meanwhile, are reporting wait times of about two weeks, so there is some variation in how quickly devices can get serviced.

After Apple admitted to slowing down older devices, the company responded with a discounted battery replacement program, allowing out-of-warranty iPhones to get a brand new battery, which should result in a faster device (and better battery life). With possible delays in service, it appears plenty of people around the globe are scrambling to get their phone’s battery replaced.

As they should, because it means their iPhone 6 won’t feel so sluggish when trying to launch and use apps. For Apple, it means owners of older iPhone models may forgo upgrading to a newer device. Whether this whole situation will have a longterm affect on iPhone sales remains to be seen, but if you have an iPhone 6 or newer, you should get a battery replacement as soon as possible.