Books, it turns out, take a long time to write. That’s what Game of Thrones fans discovered when the HBO series suddenly overtook George R.R. Martin’s novels and suddenly didn’t have any source material to draw on. Outlander, the time-traveling historical drama, has just reached a similar situation and has found itself trying to figure out where to take the story once it overtook the books Diana Gabaldon has written so far.

“In season eight, we kind of had a Game of Thrones situation,” Charles Vandervaart, who has played William in Outlander since season seven, told our very own Ashley V. Robinson at C2E2 this year. “Where we’re past the books now. We had to… we did a lot of talking to Diana [Gabaldon], the writer, about what she thinks is going to happen in the final book that she writes. So there has been a little bit of collaboration there on the book side and the film side.”

Although the upcoming Outlander season eight will take the show up to the end of where Gabaldon plans for the series, it is by no means the end of the Outlander TV show. A new series set before the events of the original books, titled Outlander: Blood of My Blood, has already been greenlit by Starz. While it isn’t based on any of her books, the collaboration with Diana Gabaldon will continue as she has been confirmed as an executive producer on the new show.