Uh oh, 33-year-old Michael Helkvist, a financial adviser from Hertfordshire, has a problem.
Fortunately the O2 Academy in Brixton is dealing with it.
Helkvist told BuzzFeed: "On arrival at the 02 Academy in Brixton, nervously awaiting Jamie xx to take to the decks, I ordered a can of Tuborg from the bar, because the only other option was a bottle of Carlsberg, and I'd rather drink my own urine.
"The barman asked me for £5.25 and I replied, 'I asked for just one can mate, not a four-pack.'
"He laughed out loud in a way that sounded like he had heard that line 500 times that night already, but still snatched my £10 from my grasp. He then handed me back my my change, depressingly made up of just coins, in exchange for a can poured so expertly into a plastic cup that half of the contents came out as warm froth."