McDonald’s is super-sizing the U.K. children’s book market by replacing its Happy Meal toys with books.

As part of a month-long promotion with HarperCollins, the fast food chain will give out nine million copies of Michael Morpurgo’s Mudpuddle Farm book series.

According to The Telegraph, “In 2011, sales of children’s books averaged 1.16 million per week “ 6.4 million in a four week period “ which means that McDonald’s will be handing out considerably more children’s books than are usually sold in the U.K. in the same period.”

The promotion is supported by the National Literacy Trust and Booktrust, a charity which gives away over 5 million books a year, however, health activists have called the move a “cynical marketing ploy.” Morpurgo, who is the U.K.’s former children’s laureate and author of the popular War Horse, is donating royalties from the McDonald’s deal to his charity, Farms for City Children.