iOS 11 has already had more than its share of show-stopping bugs, and now there’s another: iOS 11.3 is apparently disabling some iPhone 7 and iPhone 7 Plus microphones, triggering software failures that require a hardware repair. According to MacRumors and forum commenters, Apple is beginning to acknowledge the issue by offering to repair affected out-of-warranty devices for free, having previously assessed a $349 repair fee and guided users to purchase new iPhones instead.

The issue apparently manifests as a grayed-out speaker button during phone calls, and can prevent users from being heard during FaceTime video chats and phone calls. In that case, an authorized repair center’s audio diagnostic test will bring up a “device could not detect dock” or “accessory not supported” alert, which will entitle the user to an out-of-warranty repair exception, most likely at no charge.

Although it’s unclear why iOS 11.3 would trigger this issue, Apple recently had to release a software update to keep certain devices from rejecting certain replacement screens, suggesting that some OS-level component verification may be going awry. It’s also possible that the microphone problem is unrelated. In any case, the total number of online reports of the issue appears to be small by comparison with problems such as MacBook keyboards.

MacRumors notes that the iPhone 7 and iPhone 7 Plus microphone problem was acknowledged by Apple to Apple Authorized Service Providers in an official document this week, but that the memo may not have circulated to all of the company’s repair personnel. The site suggests requesting escalation to a senior AppleCare advisor in the event that a repair technician is unable to assist with the problem.