Linda Hamilton may be a badass in the “Terminator” movies, but her booty needed a boost for the upcoming franchise installment, “Terminator: Dark Fate.”

During an appearance on the BBC’s “The Graham Norton Show” — alongside the Terminator himself, Arnold Schwarzenegger — Hamilton shared that despite an intense, yearlong workout regimen prior to filming, she didn’t have the pert posterior that the filmmakers wanted for her longtime character, Sarah Connor.

“I worked out, leaned out, worked for a year, didn’t have carbohydrates for a year. And then I show up on set and they’re like, ‘Well, we have to build you a butt,’ ” said Hamilton, 63, “which is interesting after a year of working out, you know, and leaning down, they had to actually add ass.”

While Hamilton didn’t give specifics about how much faux fanny was actually added to her deficient derrière, we do know more about her workout whirlwind leading up to filming. She worked with trainer Mackie Shilstone, tennis ace Serena Williams’ longtime fitness coach, who recently told Deadline that when Hamilton started working out, she was “a 61-year-old, out-of-shape female in need of body composition adjustment.”

Over the first three months alone, Shilstone put her through six days a week of rigorous circuit, core and cardio training — including crunches, chest presses, rows and lunges. He also switched up her nutritional intake to include “prescriptive meals” with lean protein, “ample” greens and healthy fats that were delivered to her home twice weekly to complete her “dramatic transformation.” In the final nine months, Hamilton was put through agility exercises, combat training and sprint work at a high school football field and was reborn “an Industrial athlete.”

“No way we were going to let a stunt double take her place,” said Shilstone. “Or worse, put her in the position to get pushed around by a younger adversary,” adding that she dropped 15 percent of her body-fat mass by the time she was ready to hit the set.

The result? Writer James Cameron told Shilstone that his star looked “ripped and shredded.” And apparently ready to kick more Terminator butt with help from Schwarzenegger, who told Norton that his cyborg had been lying low in public and blending in as a “drapery salesman” before Sarah Connor’s return.

“Terminator: Dark Fate” hits theaters Nov. 1. It also stars Diego Boneta, Mackenzie Davis, Gabriel Luna and Natalia Reyes.