An Apple spokeswoman told The New York Times that a manufacturing defect has affected a “very limited” number of iPhone.
The issue causes shortened battery life and longer charging times.
“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,” Teresa Brewer, an Apple spokeswoman, told the publication. “We are reaching out to customers with affected phones and will provide them with a replacement phone.”
The exact number of affected units wasn’t specified, but the statement suggests that a few thousands may experience such problems.
Apple may contact affected users to replace their phone.