A man was robbed by two men and told to hand over his belongings.
The 22-year-old victim was walking along Eyam Mews, in Glossop, at about 3.30am on Monday, April 6 when he was stopped by the offenders near to a row of garages.
One of the robbers was holding a knife and told the victim to remove any valuables from his pockets and place them on the floor.
The offenders told the victim to run off after he had handed over a Nokia mobile phone. He later called police.
The robber with the knife was white, aged about 16, about 5ft 5ins and of slim build. He was wearing a black woolly hat, a snood covering the lower half of his face, a black Adidas top and tracksuit bottoms.
The second was white, about 17 or 18, 5ft 8ins to 5ft 9ins, and also of slim build. He was wearing a grey Adidas top, a blue body warmer, grey trousers and a hat.
Officers investigating the offence want to hear from witnesses or anyone who recognises the descriptions of the robbers.
Anyone with information should call Derbyshire police on 101, quoting crime reference 14028/15. You can also call Crimestoppers, anonymously, on 0800 555 111.