D.C. United signed center back Brandon McDonald to a new contract Tuesday.

McDonald, 25, was acquired from the San Jose Earthquakes for allocation money in June and has become a crucial part of United's defensive success. In nine matches, he has contributed to four shutouts.

"Brandon has quickly asserted himself into our side and has helped to solidify our backline," said United General Manager Dave Kasper. "He is a very talented central defender with a huge upside, and we are thrilled to have reached a deal to keep him at D.C. United."

Previously, McDonald spent two and a half seasons in San Jose, appearing in 58 MLS games (54 starts), including eight starts in 2011. He was drafted by the Los Angeles Galaxy with the 46th pick in the 2008 MLS SuperDraft and played 16 games for the Galaxy prior to joining San Jose in 2009.

Per club and Major League Soccer policy, specific terms of the deal were not disclosed.