Nearly 400 litres of homemade alcohol was seized in Irish prisons last year.
According to Freedom of Information figures released to Newstalk, nearly half of the total was found in Mountjoy jail.
A total of 391.5 litres of 'hooch' was seized in eight jails across the country last year.
49% of last year's total was seized in Mountjoy Prison - involving 192 litres of homemade alcohol.
That's followed by 82 litres in Portlaoise, 41 in Wheatfield Prison in Dublin and 35 in Cork jail.
The total figure is almost exactly the same as 2019, when 395.5 litres of hooch was seized.
John Cuffe, a criminologist and former prison officer, says such alcohol has been popular among inmates for many years.
He said: "It's quite easy to make, and it's quite easy to store.
"It's generally made up of fruit - apples, oranges, bananas, sugar. Mixed in with that, white bread is soaked... and then it's [all] put away to ferment.
"It normally goes in large two-litre bottles. They tend to stick it under beds, near radiators, storage areas where cleaning goods are kept."
He said it's the "nearest thing" inmates can get to alcohol in a prison environment, but it's likely only a "small amount" of people involved in making it.
Figures revealed last month showed there were over 1,200 drug seizures in Irish prisons last year.