Fire inspectors in Thunder Bay believe a laptop left charging and running on a couch overheated, causing a house fire last week on Ryerson Crescent.
The blaze caused what the fire service estimates as hundreds of thousands of dollars in damage.
Eric Nordlund, Fire Prevention Captain with Thunder Bay Fire Rescue said the incident serves as a warning to keep charging laptops off soft surfaces, such as a bed or couch.
"So the couch is obviously soft, the material on the couch is soft, and so it would block any of the vented areas that the internal fan would use to cool the computer. Potentially the laptop overheated and malfunctioned."
Another possibility in the Ryerson Crescent incident, he said, is that a transformer connected to the computer may have overheated.
Thunder Bay Fire Chief John Hay said people should be cautious where they leave laptops running.
"Never leave an operating laptop on a soft surface which may impede the airflow from the cooling fan or prevent dissipation of heat."