The man who created the Dothraki and High Valyrian languages on HBO’s Game of Thrones spilled all the tea while on BuzzFeed News’ morning show AM to DM — from how he created the languages to how he feels about actors who sometimes fumble his precious words.

“When I created Dothraki, it was for a competition with other language creators,” David J. Peterson said Friday, adding that it took him “maybe a month” to come up with the language.

The competition to create the Dothraki language was specifically for the show’s “internal pilot,” he added. Peterson used the first four books in George R.R. Martin’s A Song of Ice and Fire series as the foundation for both the Dothraki and High Valyrian languages.

And he didn’t have a lot of material to work with, he said.

“There were 56 words for Dothraki; about half of them were names and like three sentences,” Peterson said of Martin’s books. “With Valyrian there was really just four words and two sentences. There was ‘valar morghulis,’ ‘valar dohaeris,’ and then ‘valonqar’ and that was it.”

(“Dracarys” is a Martin original word too, by the way).

Peterson said he made sure everything he did incorporated Martin’s material so that after he was done, “it wasn’t like my language looked totally different.”

Emilia Clarke, who plays Daenerys Targaryen on the show, once said producers can’t tell if she flubs a line in Dothraki. But Peterson said Friday that he notices anytime an actor messes up, but it doesn’t annoy him like it used to.

“It used to initially, but you know, after working on like 20 shows and movies, I learned to roll with it,” he said. “The way I look at it is that most of the time the performances are pretty good and then sometimes the performances are absolutely stellar and then every so often it’s utterly terrible.”

If you want to brush up on your Westerosi language skills before the premiere of Game of Thrones’ final season, you can check High Valyrian on Duolingo, a course Peterson himself created.

“Grammatically, it’s pretty difficult,” he said. “But it’s not like anyone is hanging over you checking to make sure you’re fluent … you can just jump on whenever you want on your phone and just kind of be really casual about it.”

Watch Peterson’s full interview below: