Zoo keeper Michal Krause has discovered the perfect way to cut out monkey business when he tucks his orangutans up at night - by reading them a bedtime story.
The two playful primates used to drive keepers ape at Poland's Gdansk Zoo until Michel, 36, started to read to them.
"They were repeat offenders, always causing trouble," said Michal of Albert, 40, and Raya, 35.
"If you gave them a fruit snack they'd throw it around, if you tried to wear them out with play, they'd just get hyper.
"I didn't know what to do until I pulled out a book I was reading during a break and within a couple of minutes they were trying to read over my shoulder," he added.
Now the arty apes have even developed their distinct literary tastes.
Albert likes English literature like Jane Austen and Charles Dickens, while Raya is a fan of thrillers and drama.
"Albert's favourite book is Pride and Prejudice while Raya like German fiction, like the Winnetou native American stories by Karl May.
"But they both like cookery books and when we're doing dramatic readings they like me to act out all the movements," said Michal.
"Now they go to bed quietly and peacefully as long as they get their stories," he added.