The next novel in the series adapted by HBO as "Game of Thrones" is not finished.
So HBO's sixth season of the wildly popular show, slated to start in April, will almost certainly air before its source material is published.
"I am months away still ... and that's if the writing goes well. (Sometimes it does. Sometimes it doesn't)," Martin wrote.
Writing on "The Winds of Winter" has not been going well.
"I tried, I promise you. I failed. I blew the Halloween deadline, and I've now blown the end of the year deadline. And that almost certainly means that no, THE WINDS OF WINTER will not be published before the sixth season of GAME OF THRONES premieres in April," Martin said in his post, which was tagged with "current mood: depressed."
Will the show spoil the novel?
"Maybe. Yes and no," he wrote. Martin said he never thought the show would catch up with the books, yet it has.
"Given where we are, inevitably, there will be certain plot twists and reveals in season six of GAME OF THRONES that have not yet happened in the books," he said.
The looming deadline and the stress of not finishing got to him. "The fewer the days, the greater the stress, and the slower the pace of my writing became," Martin wrote.
Still, regardless of the release order, "you can still enjoy the hell out of both."
Fans were very appreciative and supportive of Martin's update. His post received more than 1,000 responses before he closed the comments
"Just keep on truckin,' " one fan wrote. "The fact that you're working hard is enough to sate me."
Martin thanked fans in a second post Saturday.
"The outpouring of support in response to my post on THE WINDS OF WINTER has been astonishing," he said.