Buffy fans, rejoice! Oz Seth Green Will soon reunite with Willow Alyson Hannigan as a guest star on How I Met Your Mother.

Green will appear on the sitcom as Daryl LaCoutre, a man who considers Lily (Hannigan) and Marshall (Jason Segel) two of his best friends from college. Twelve years later, the pair run into him, but they have no clue who he is. LaCoutre apparently goes into stalker-sounding territory, as he is “creepily obsessed with having them [Lily and Marshall] in his life.”

The episode is tentatively schedule to air on CBS on December 10.

Until then, True Blood fans will want to tune into the show on November 12, when Joe Manganiello is set to begin his two episode arc on the hit series.