PORTLAND, Maine (AP) — A landlord sentenced to jail time following a fire that killed six people in Maine has filed an appeal that cites a vague fire safety code as a factor in the blaze.

Gregory Nisbet was handed a short jail sentence for code violations stemming from the 2014 apartment fire, which was the deadliest in Portland in decades. The Portland Press Herald reports Nisbet has filed a brief that argues the fire code in unconstitutionally vague.

Nisbet argues that the code does not put "an ordinary person" on notice that his actions aren't legal.

The fire started because of improperly discarded smoking materials on a porch. People on the upper floors of the apartment were left trapped as the fire consumed the building.

Nisbet was acquitted of manslaughter at trial in 2016.