One of television’s most geek-friendly actors is heading to its most geek-friendly show.

Nathan Fillion, of Firefly acclaim, will cameo in an upcoming episode of The Big Bang Theory. Appearing as himself, Fillion will appear in February 19th’s episode.

Atop of Firefly, Fillion has a long resume with science fiction and comic book roles, starring in Joss Whedon’s Firefly, Dr. Horrible’s Sing-Along Blog, Buffy The Vampire Slayer, and more. He has also voiced Hal Jordan in several Justice League animated features.

In the upcoming episode,Raj and Leonard--devoted Fillion fans--stumble upon the actor while eating at a restaurant. But before the two ask for an autograph, they can't decide if the man they're seeing is really the famed actor, or just a look alike.

The Big Bang Theory airs Thursdays at 8:00 p.m. on CBS.

Via Entertainment Weekly.