Credit: Todd Williamson/

Zooey Deschanel is about to become one of the coolest aunts in Hollywood.

The 31-year-old She & Him singer's sister, Bones actress Emily Deschanel, announced she is expecting her first child with her writer-actor husband David Hornsby on Thursday.

"I am super excited to be an aunt!" Zooey tweeted later that evening.

Emily, 34, and Hornsby -- who plays Matthew "Rickety Cricket" Mara on FX's It's Always Sunny in Philadelphia -- tied the knot in a private L.A. ceremony on September 25, 2010.