A shoplifter was jailed for three weeks after taking £15 washing liquid from a Wilko store.
The penalty was ordered because Brian Lowe, 56, was already under two suspended prison sentences, city magistrates heard.
He is due to appear on a video link from prison to discover how much should be added to the three weeks.
The JPs were told this was necessary so a full investigation can be carried out to find the exact length of the earlier suspended terms.
Compensation of £15 was ordered from Lowe, of Millers Court, Radford. He pleaded guilty to theft from Wilko on May 11 and admitted breaking the terms of two suspended sentences.
Donna Fawcett, prosecuting, said one earlier offence involved taking Persil tablets and selling them to buy food.
"He sold items in pubs," she added.
Chris Wall, mitigating, told the court: "This is a person with a number of issues and he is certainly a highly vulnerable individual.
"His record is certainly not enviable."
Lowe was living in a special unit where staff help tenants with a range of problems, added Mr Wall.
To receive one WhatsApp message a day with the main headlines, as well as breaking news alerts, text NEWS to 07790 586202. Then add the number to your phone contacts book as 'Nottingham Post'. Your phone number won't be shared with other members of the group.
