An Indiana State Police sergeant is warning drivers that putting holiday lights on vehicles is not only dangerous but also illegal.

State Police Sgt. Glenn Fifield says if he encounters a car with Christmas lights wrapped around it, the driver could face a fine.

“I would probably be complimentary about how fancy of a design they have, but then we will probably have to have a conversation about why it’s not appropriate and why it’s not legal,” he said.

No U.S. state allows Christmas lights on vehicles for regular road use. Federal and state regulations make the moving displays illegal, though some states issue special permits for parades and events.

Fifield shared a post on Facebook Tuesday about a vehicle recently pulled over for displaying Christmas lights. His message wasn’t to be a “Grinch,” but to warn that such lights could lead to a traffic stop.

“From what I understand, there are some window tint places that are installing these lights for people like this, but that’s a different story,” he added.

Fifield also highlighted the safety risks, noting that drivers behind these cars may get confused, making it difficult to see when the car’s brake lights are on.