The White Sox are adding to their farm system this offseason. The White Sox announced Thursday morning that they have acquired minor-league pitcher Thyago Vieira from the Mariners in exchange for international signing bonus pool money. Vieira, who rated as the No. 8 prospect in the Mariners organization spent majority of his time in the minor leagues last name, switching between Class AA Arkansas and Class AAA Tacoma. He combined to go 2-4 with a 4.00 ERA (24 ER/54.0 IP), four saves and 46 strikeouts in 41 appearances. The 24-year-old right-hander limited right-handers to a .194 (25-129) average. Vieira also made one appearance with the Mariners last season. He retired all three batters faced in his major-league debut against Baltimore on Aug. 14.