Colts add quarterback Josh Johnson

The Indianapolis Colts on Friday signed quarterback Josh Johnson and waived cornerback Shaun Prater.

The roster moves could be an indication the team is expecting Andrew Luck, who is battling an injury to his throwing shoulder, to be unavailable Sunday. Or it could be purely for insurance.

Johnson played for Jim Harbaugh in college and has familiarity with Colts offensive coordinator Pep Hamilton's scheme.

Johnson has played in 29 games (five starts), recording five touchdowns and 10 interceptions in his pro career. Most recently, he spent time in training camp with the New York Jets and Cincinnati Bengals.