Credit: Larry Busacca/Getty Images

Craig Ferguson and his wife, art dealer Megan Wallace, are expecting a baby, The Late Late Show host, 48, announced on Twitter Wednesday.

"Holy crackers! Mrs F is pregnant. How did that happen?" he Twittered. "Oh yeah I know how. Another Ferguson arrives in 2011. The world trembles."

The two - who wed in December 2008 - are parents to Milo, 9, Ferguson's son from a previous relationship.