IPhone owners should beware picking up bad vibrations from powerful motorbikes, as they may damage camera systems, Apple has said.
The technology giant published a warning iPhones should not be attached to powerful bikes, in a support document spotted by MacRumors.
Engine vibrations can harm phones' optical-image stabilisation or closed-loop autofocus systems, it says.
Owners of scooters and mopeds should also use "vibration-dampening mounts".
On social media, several users have said their phones have been damaged after being attached to a motorcycle.
And Apple says several models of iPhone are susceptible to the damage.
The affected systems are designed to improve picture quality by counteracting movement, vibrations, and the effects of gravity.
But high-power or high-volume motorcycle engines generate "intense high-amplitude vibrations", the support page says, which can be transmitted through the frame and handlebars.
"Direct exposure to high-amplitude vibrations within certain frequency ranges may degrade the performance of these systems and lead to reduced image quality for photos and videos," it says.
The solution is to refrain from attaching iPhones to the bike in the first place - something commonly done for navigation.
Camera performance can "degrade" if attached to high-volume, high-power motorbikes, Apple says.