Electronic cigarettes, the hip alternative to smoking traditional tobacco cigarettes, may pose a fire hazard when they are put in checked luggage on planes.

The Federal Aviation Administration has issued a warning to commercial airlines, suggesting that they require passengers to put e-cigarettes in carry-on bags only.

The International Civil Aviation Organization, an agency of the United Nations, issued a similar recommendation in December.

The FAA warning cited an incident in August at Boston’s Logan Airport where an e-cigarette in luggage in the cargo hold of a plane caused a fire that spurred an airplane evacuation on the tarmac.

This month an e-cigarette in a checked bag that had missed its flight from Los Angeles International Airport started a fire in the airport baggage area, according to the FAA.

“These incidents and several others occurring outside of air transportation have shown that e-cigarettes can overheat and cause fires when the heating element is accidentally activated or left on,” the FAA said.