Auckland's Central City Library has solved the mystery of books vanishing off shelves, and then discovered wedged in peculiar places around the building.
It turns out the city's homeless were stashing their favourites because they can't borrow them without a home address.
"A lot of our street community were wanting to put them underneath the couches or under book shelves and kind of hiding them in places," librarian Sean Taylor said.
"Anywhere they thought was theirs and they can keep it there.
"And for a librarian it's really weird, we're like 'oh what's this book doing here?' and we've put it back."
But when the staff discovered the homeless were responsible, they came up with a solution and informed their rough sleeping patrons.
"We actually have this service where you can hold it on the shelf, and you can come back in the morning and get stuck back in," Taylor said.
With Auckland's central library a refuge for the city's homeless during the day, dozens will routinely come in to escape the cold and get lost in a book.
But without a proper address they can't become a library member.
"They're really well read. We've got a guy who I've had a discussion about the meaning of words and the reference section and it's the kind of intellectual conversation you'd expect from an academic," Taylor said.
The message? Don't judge a book by its cover.