The Vikings signed CB Frank Walker, a journeyman who will take the place of injured CB Cedric Griffin on the roster.
Griffin suffered a torn ACL less than 10 months after suffering a similar injury and was placed on injured reserve Wednesday after fighting to get back on the field in Week Three.
Walker has played seven years in the NFL, recording seven interceptions in 82 career games. Last season, he played in 14 games and started one for the Ravens, collecting 16 tackles and one interception. He worked out last week for the Saints but did not sign.
The team also signed CB Marcus Sherels to the practice squad and released TE John Nalbone from the same unit.