In the Marvel Cinematic Universe, only two beings have proved capable of Thor’s hammer: Thor himself and the Vision (though Captain America did make the hammer budge a little bit). But that was Mjolnir. Thor has a new hammer, and someone else was able to lift that one in Avengers: Infinity War, the Guardians of the Galaxy member Groot.

Groot was able to hand Thor the new hammer, Stormbreaker, during a key moment of Avengers: Infinity War, even sacrificing one of his own limbs to serve as the hammer’s handle. During the Avengers: Infinity War Vudu Viewing Party, one fan asked directors Joe and Anthony Russo if this meant Groot was also “worthy.”

The Russos clarified that the worthiness enchantment that Odin placed on Mjolnir was specific to that original hammer and does not transfer over to all of Thor’s weapon.

“Mjolnir requires worthiness, not Stormbreaker,” the Russos tweeted from the official Avengers Twitter account.

Thor traveled with Groot and Rocket on his journey to forge a new weapon. The Russos also explained why they grouped those heroes together in Infinity War.

“Tonally, [it’s] one of our favorite scenes in the movie. Thor is at his lowest point that he’s been in any of the films. He’s lost everything. And he’s been partnered up with Rocket, who is perhaps one of the least emotional characters in the Marvel universe,” Joe Russo said. “We thought that would be an interesting pairing if Thor had to pour his heart out to a character who — to a certain extent — lacks empathy, and see if it would affect that character in some way. I think what we love so much about the scene is how complicated the scene is. It’s at times absurd and funny and completely tragic.”

Anthony Russo added, “It’s a threshold moment for the character where you really realize he has nothing left. And for us as storytellers, it’s a wonderful place to take a character when you strip everything away. That’s something that we tried to do with Captain America throughout our run with him, so to have Thor in a similar place and to be able to find what’s left when you take everything away from Thor, it’s a great journey for us as storytellers."

Avengers: Infinity War releases on Digital HD on July 31 and on Blu-ray on August 14th.