Trainspotting star Ewan McGregor could not resist a joke on Twitter about his famous film as he watched BBC Four's Trainspotting Live.
The actor is currently filming Trainspotting 2, the sequel to the original 1996 movie which first made his name around the globe.
Ewan, who is reprising his role as heroin addict Mark Renton, tweeted on Wednesday that the people on his TV screen were not "on the skag" - a slang term for heroin.
Broadcast over three nights, Trainspotting Live captured the imagination of viewers as a team of enthusiasts and expert spotters reported live on a range of rail stock.
The programme was helmed by Peter Snow, mathematician Dr Hannah Fry, presenter Tim Dunn and engineer Dick Strawbridge, along with a team of train enthusiasts.
It has won praise from viewers for its quirky subject and interesting content.
Viewers who had their say on Twitter couldn't help singling out Tim for extra praise. Brought up playing with model trains, his enthusiasm and knowledge proved a definite winner with fans.