The 66-year-old actor Tweeted on Sunday about his return to the franchise and shared some pictures of his time with Fisher in the previous movies. The two starred as twins Luke and Leia through 5 previous Star Wars films.

“It’s bittersweet facing my final chapter without her-She is simply irreplaceable,” he wrote. “I’m finding solace in the fact that she won’t BE replaced & would love the worldwide outpouring of affection from those who loved her when they heard the news.”

It's bittersweet facing my final chapter without her-She is simply irreplaceable. I'm finding solace in the fact that she won't BE replaced & would love the worldwide outpouring of affection from those who loved her when they heard the news.#CarrieOnForever pic.twitter.com/7ueMqBxQwa

— Mark Hamill (@HamillHimself) July 29, 2018

On Friday, Disney and Lucasfilm revealed the official cast list for the ninth trip to a galaxy far, far away and it contained one major surprise: Fisher is back as Leia, despite her shocking death in 2016.

According to the studio’s online announcement, production on the newest Star Wars adventure is expected to commence on Aug. 1, and Fisher is among the listed cast members returning for the film, thanks to some unused footage shot for Star Wars: The Force Awakens.

Returning director J.J. Abrams, who co-wrote the script for Episode IX alongside Chris Terrio, said in a statement, “We desperately loved Carrie Fisher. Finding a truly satisfying conclusion to the Skywalker saga without her eluded us. We were never going to recast, or use a CG character. With the support and blessing from her daughter, Billie, we have found a way to honor Carrie’s legacy and role as Leia in Episode IX by using unseen footage we shot together in Episode VII.”

Fisher died December, 2016 at age 60 of a cardiac arrest.