Three years after their divorce was finalized, Deryck Whibley has filed legal documents to drop ex-wife Avril Lavigne's last name. Credit: Denise Truscello/WireImage

Who knew? When Deryck Whibley married Avril Lavigne in 2006, he took her last name. Now, three years after their divorce was finalized, the 33-year-old Sum 41 rocker has filed legal documents to drop the "Lavigne" from his name.

According to TMZ, Whibley secretly changed his name to Deryck Jason Lavigne Whibley after his wedding to the 29-year-old singer. The couple announced their split in 2009 and their divorce was finalized in 2010.

TMZ reports that Whibley filed documents in L.A. County Court on Thursday, Nov. 7, to change his name back to Deryck Jason Whibley.

Lavigne is now married to Nickelback frontman Chad Kroeger. The Canadian couple tied the knot in the South of France in July 2013 after one year of dating. In the June/July issue of Nylon, the "Let Me Go" singer revealed that she first met Kroeger while she was dating Whibley more than a decade ago. "Wild, right?" she laughed. "I was 17, and 'Complicated' had just come out.'"

"He didn't even know who I was at that point!" she said of Kroeger, 38. "I had just gotten on the radio."