The worst-kept secret of the superhero film universe is now official: Marvel has finally confirmed that Vin Diesel is voicing Groot, the extraterrestrial plant monster of comics lore, in James Gunn‘s Guardians of the Galaxy. The Fast & Furious star has been teasing the role for months and posted a photo over the weekend posing with his onscreen alter ego. Gunn added via Facebook: “Yep it is completely official. AND he’s amazing. I never knew someone could say I AM GROOT so many different ways and with such feeling (and that sounds like I’m kidding but I’m not!)” Diesel stars in the cosmic superteam actioner alongside Chris Pratt as Star-Lord, Bradley Cooper as Rocket Raccoon, Zoe Saldana as Gamora, Dave Bautista as Drax. The Marvel pic hits theaters August 1, 2014. See any resemblance below?