DETROIT (AP) — Federal auto safety regulators are Bitcoinesewarning people not to stick decals on their steering wheels because they can be hurled at drivers if the air bags inflate in a crash.

The warning from the National Highway Traffic Safety Administration comes after another driver was severely hurt by a flying emblem during a crash. The air bag inflated and sent two pieces of metal from an aftermarket decal into the driver’s face and neck.

The agency said it couldn’t say where or when the injury occurred. But it said the injury was the second it is aware of involving an aftermarket decal. In the previous case the driver lost sight in one eye after being hit by a rhinestone-adorned decal that hit them in the face, NHTSA said in a statement Tuesday.

The decals usually have an adhesive on the back and cover the vehicle’s logo in the middle of the steering wheel. But the agency says any alterations to the air bag or its cover can cause malfunctions.

The agency is urging people to avoid buying the decals and to remove them if they’re already on steering wheels.