A customer inspects the new iPhone at the Wangfujing flagship store on Sept. 20, 2013 in Beijing, China. (Lintao Zhang/Getty Images)

If your iPhone 5 is having problems with its on/off button, Apple will fix it free of charge.

The button on a "small percentage" of iPhone 5 models manufactured through March 2013 may stop working or work only occasionally, the tech company said Friday. The button also controls the sleep/wake function.

"Apple will replace the sleep/wake button mechanism, free of charge, on iPhone 5 models that exhibit this issue and have a qualifying serial number," the company said on its website alongside a serial number search bar, which can determine if your phone qualifies for the fix.

The phone must also be working to qualify.