Nathan Fillion's TV home might be ABC these days, but the Castle star will jump to CBS for one night.

Entertainment Weekly broke the news that the beloved actor will appear on the Feb. 19 episode of the hit sitcom The Big Bang Theory.

In "The Comic Book Store Regeneration," Howard and Raj argue whether the man in the restaurant with them is actually Fillion or someone who looks like him. After confirming, they then build the courage to ask him for a photo.

As it turns out, the plot is somewhat similar to a Season 2 episode called "The Terminator Decoupling" that featured Fillion's Firefly and Serenity co-star Summer Glau.

The episode premieres Thursday, Feb. 19, at 8 p.m. ET/PT on CBS.