Apple is warning users of its 1st generation iPod nano of potential overheating problems.

According to Apple, the nanos in question were sold between September 2005 and December 2006. While the problem only happens in “very rare cases,” Apple does recommend customers stop using the 1st generation iPod nano.

Apple posted a note on its Website with instructions on how to order a replacement unit. There are also instructions on how to identify your iPod as one of the affected models.