Harper Lee’s second novel, Go Set A Watchman, has sold over 1.1 million copies through booksellers in the U.S. and Canada, according to HarperCollins, becoming the fastest-selling book in the company’s history.

“First week sales of Go Set a Watchman have far exceeded our expectations,” said Brian Murray, President and CEO of HarperCollins, in a statement. “Bringing this book to market has been an amazing effort by thousands of people – from our publishing teams to booksellers large and small. We are thrilled to see readers responding to this historic new work from an iconic author like Harper Lee.”

There are currently more than 3.3 million copies of Go Set a Watchman in print, and HarperCollins has gone back to print the title multiple times. A Spanish-language edition of the book was also printed in more than 150,000 copies.

Watchman, which was published on July 14 after months of speculation and hype, also set records at Barnes & Noble and Barnes & Noble said that the book set a record of adult fiction books sold in a single day, and Amazon reported it was the most pre-ordered book since 2007’s Harry Potter and the Deathly Hallows.