Eden Prairie, MN (SportsNetwork.com) - The Minnesota Vikings have added an additional year to the contract of John Sullivan, extending the stalwart center's deal through 2018.

The Minneapolis Star-Tribune also reported that the Vikings raised Sullivan's base salary to $5.9 million for the upcoming season.

Entering his eighth season with Minnesota, Sullivan has anchored the team's offensive line since being inserted as a starter in 2009. The 29-year-old has opened 93 of a possible 96 games over that span, missing the other three due to injury. He hasn't missed a game since 2011.

The 2008 sixth-round pick was named a first team All-Pro by the Pro Football Writers Association of America in 2012, the year in which Adrian Peterson rushed for 2,097 yards en route to winning the NFL MVP honors.