When little Pax learns to write, he's going to have one heck of a name to practice.
Pax Thien Jolie officially had Pitt added to his last name Thursday following proceedings in Los Angeles County Superior Court.
Pax Thien Jolie-Pitt was adopted from a Vietnamese orphanage in March.
Mom Angelina filed the court papers in April to have daddy Brad's last name legally added to the 3-year-old's moniker.
All three of Pax's siblings – Maddox, Zahara and Shiloh – also have Jolie-Pitt as their last name.