In a rare act, Apple admits its latest iPhone is less than perfect.

The company has confirmed that a “manufacturing issue” in some iPhone 5S models has led to battery issues for some customers, the New York Times reports.

Speaking to the Times, Apple spokeswoman Teresa Brewer said, “We recently discovered a manufacturing issue affecting a very limited number of iPhone 5S devices that could cause the battery to take longer to charge or result in reduced battery life. We are reaching out to customers with affected phones and will provide them with a replacement phone.”

The admission comes after complaints from iPhone 5S owners, who expected significantly better battery life than Apple’s previous iPhones. Naturally, Apple didn’t offer many specifics: We don’t know how many units are affected, and we don’t know what the company will do to resolve the problem.

While manufacturing issues are never ideal, the situation could be worse for Apple. A battery defect, for example, could have affected many more iPhone 5S models and could have led to a recall. When Apple released the iPhone 4 a few years ago, it had to give away free bumper cases and admit that the phone’s antenna design caused issues (the “antennagate” fiasco).