Bengals sign Marshall Koehn, waive Derron Smith

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The Bengals signed kicker Marshall Koehn. They waived safety Derron Smith in a corresponding move.

Kicker Randy Bullock strained his back Monday, prompting the Bengals to sign Koehn as insurance.

Koehn, a first-year player, originally signed with the Dolphins as a college free agent out of Iowa in 2016. Miami waived him before the start of the season, and he was not with a team last season.

He played in all four of the Vikings’ preseason games this summer, but Minnesota waived him Sept. 2.

The Bengals made Smith a sixth-round choice in 2015. He played in three games this season, making one special teams tackle, and has played in 31 games in his career.