The White Sox made the four-year, $32.5 million contract extension for shortstop Alexei Ramirez official Thursday and also announced they had signed outfielder Lastings Milledge to a minor league contract.

Milledge, a former first-round pick, was invited to spring camp and will be in the mix to become the team's fourth outfielder. At age 25, he has played for Mets, Nationals and Pirates with a career batting average of .269. Last season with Pittsburgh, he hit .277 with 21 doubles and 34 RBIs in 113 games.