Washington, Mar 4 : Nicole Richie and her boyfriend Joel Madden are planning to tie the knot after knowing that they are expecting their second child, it has emerged.

The couple welcomed daughter Harlow Winter Kate Madden in January 2008, and Madden recently announced that his stunning partner is pregnant again, reports Contactmusic.

A close pal told In Touch Weekly magazine: "They are old-fashioned in some ways. Now their second baby is coming, they both want to make it legal."

And The Simple Life star has already found her wedding dress - a vintage Yves Saint Laurent gown.

The insider adds, "It''s been hanging in the back of her closet. She always planned to wear it on a very special occasion." (ANI)