Robert Kirkman, the creator of The Walking Dead comic book series, has expressed his disappointment in the way George R.R. Martin allowed HBO’s Game of Thrones to spoil aspects of his books.

In a recent Rolling Stone profile, Kirkman revealed that he is firmly on the side of fans who read Martin’s A Song of Ice and Fire series and are upset that the newest season of Game of Thrones contains spoilers for the books. Martin has apologized to fans in the past for not finishing his upcoming installment, The Winds of Winter, on time, admitting that while his books and the show diverge drastically from one another in terms of plot, there are still key moments that the show will give away.

Kirkman is no stranger to writing his work in tandem with its television adaptation, but has said in the past that he doesn’t have to worry about The Walking Dead show catching up to him because his comics are so far ahead. However, he also told Rolling Stone that even if the show caught up to him, he would never let it spoil his stories.

“That’s the one thing I’m disappointed in George R.R. Martin for doing,” Kirkman said. “He should have just been like, ‘F–k you. You make it up now, I’ll get to mine when I’m ready.”

Game of Thrones showrunners David Benioff and D.B. Weiss have also discussed this issue in the past, arguing that since the show is so different from the books, even the big reveals won’t ruin the experience for readers when they eventually get their hands on Martin’s next book.

The Winds of Winter currently has no set release date, though Martin has promised that he is working as fast he can to finish.

(Via: Polygon)