"I think we're down to our final 13 episodes after this season. We're heading into the final lap," Benioff told Variety. "That's the guess, though nothing is yet set in stone, but that's what we're looking at."
More from NBC News:
NY Republicans Ignore Ted Cruz at GOP Gala
John Kasich Supports 'Moving On' From Gay Marriage Debate
Protesters Turn Out for Trump Campaign Stops
The sixth season of the megahit HBO series premieres April 24 and will run for 10 episodes — the length of the first five seasons.
HBO programming president Michael Lombardo told Variety he was aware of the tentative plan to end the show after two more years. "That's my understanding from them right now. Those have been the conversations we've had," he told the trade publication. "Because where these narratives go, it feels like another two years to them."
He added: "As a television executive, as a fan, do I wish they said another six years? I do."