Spoiler warning! If you haven’t read the book or don’t want to know how the movie ends, turn back now!

The first American hardcover edition of “Harry Potter and the Half-Blood Prince” spanned 652 pages. Even at over two hours and thirty minutes, the film version couldn’t stuff in every battle, breath and broomstick. Director David Yates had to make a number of tough calls, including losing an important fight in the Second Wizarding War and changing J.K. Rowling’s original ending, which recounted Dumbledore’s funeral.

“We had [the funeral] in the script at one point and it was a really strange experience,” he told MTV’s Josh Horowitz recently. “But after the courtyard scene and Dumbledore’s died, it felt like going to the funeral just felt like we were suffering from ending-itis. It felt like another end.”

Yates went on to note the difference between the experiences of reading a book and watching action unfold on the big screen. “In a book you can enjoy that journey but in the rhythm of a darkened cinema, it felt like the right place to end,” he explained.

Ultimately, though, Yates’ mission is to please both the franchise’s diehard fans and those without much exposure to “Potter” lore. “The fans gets frustrated with some of the decisions we take sometimes, but we’re trying to serve not just them obviously—because we adore them and we’re grateful for their support—we’re trying to serve an audience beyond the fan base who haven’t read some of the books,” he said.

Check out the video to hear Yates talk about why cutting out elements of the book is so tricky and about one “beautiful sequence” that never made it into the film.