UK library staff have been left with a "nightmare" job after a well-meaning cleaner restacked the bookshelves in order of size after cleaning them.
Staff at Newmarket Library in Suffolk discovered the alterations after the building underwent a deep clean while it is closed due to the COVID-19 pandemic.
Head of service delivery at Suffolk Libraries Krystal Vittles shared a tweet on Thursday of the shelves saying: "You think you're having a bad week?"
"My poor colleague has just been in to do her weekly check of the library building," she wrote.
"The cleaner has started deep-cleaning the space (so far, so good) and has cleaned the shelves but has put 18.5 bays of books back in size order!"
The Sun UK reported Vittles later tweeted it was an honest mistake.
"A quick update: our cleaner at this library is a great lady," she wrote.
"Bless her for being neat and tidy. She doesn't work in libraries as such so she was just doing her best, and to be fair, the books were neat as heck.
"I might have to buy her a bottle of wine after this."
The manager of Newmarket Library told The Mirror UK it was lucky it happened during the lockdown.
"I was a bit shocked at the time as it'll take us a bit of time to reorganise them but I can see the funny side now.
"We're all still really busy at the moment running library activities online for our regular customers but sadly it looks like libraries will be closed for a while so we'll have time to sort the books out.
"Our cleaner is lovely and does a great job in the library.
"It was an honest mistake and just one of those things so I would never want her to feel bad about it."
She says the story has gone viral with thousands of retweets and has had fellow librarians get in touch.
"I think people are just pleased to be able to share any light-hearted stories at the moment as it helps to cheer everyone up. In the grand scheme of things, it's not really that important."
She says the books should be back in the right order by the time the doors reopen.