A library in Novosibirsk has canceled a quiz about the Harry Potter books, following a reader’s complaint that the quiz included questions that might encourage children to attempt the production of certain potions. According to local news website NGS, the concerned reader claimed the questions about potions posed a public danger.

The library has reportedly offered the quiz two years in a row, becoming a popular attraction among local children and adults. The quiz was available online and in person at the library. Patrons who answered all questions correctly were rewarded with a special diploma.

The library’s director told NGS that one of the reasons for canceling the quiz this year was a complaint by a woman worried that children “might become ill,” if they tried to cook the potions described in J. K. Rowling’s books.

“Nobody has ever cooked anything, so far,” the director said, “but she drew our attention to the possibility that a child might get it in their head to try.”