Network Rail has taken action to protect a new Banksy mural after it was allegedly defaced by a member of the public.
The mural, next to Birmingham's Jewellery Quarter station, depicts a couple of reindeer pulling a bench along like Santa's sleigh.
Red noses have now been spray painted onto the animals by a vandal, Birmingham Live reports.
Network Rail has now taken the "unusual step" of covering the artwork on its property with a sheet of perspex.
David Golding, interim route managing director for Network Rail's Central route, said: "As a railway family, our hearts go out to the homeless, especially at this time of year.
"Banksy's wall art has captured their plight so well. It's right we protect it so everyone can see it.
"We discourage any graffiti and we spend a lot of time removing it from around the network ... but it's not every day we get a bona fide Banksy."
On Monday, the mysterious street artist posted a video to Instagram depicting a rough sleeper lying down on the bench.
He wrote: "God bless Birmingham. In the 20 minutes we filmed Ryan on this bench passers-by gave him a hot drink, two chocolate bars and a lighter - without him ever asking for anything."
According to reports, a young man in a hoodie, thought to be in his mid-20s, sprayed the mural with red paint soon after the work was confirmed as a genuine Banksy.
The man allegedly asked onlookers whether he should "tag" the wall, before ignoring pleas not to do so.
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