Two fire engines from Falmouth were called to a reported freezer fire at the Iceland supermarket on the Moor on Sunday evening.
The crews were sent at around 6pm, after a fault in heating unit which prevents a large freezer door from freezing shut, which started burning a piece of wood.
A spokesperson for the store said: "It wasn't really a fire, it was a smouldering piece of wood.
"It caused a bit of smoke and set the alarms off.
"It didn't need two fire engines, it needed a man and a fire extinguisher."
Crews wearing breathing apparatus used a hose reel, a carbon dioxide fire extinguisher and a thermal imaging camera, and checked the area was safe.
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