Johnson allowed McIndoe to join the Sky Blues in the summer and the Scottish winger is eager to turn in a good display against his former club at the Ricoh Arena on Saturday.
But Johnson told the club's official website: "When Macca leaves any club he says there is a point to prove, but there is nothing to prove. He got a move that was right for him and us and that's what happens in football.
"When you say things like that you've got to come up with the goods. We've got to make sure we keep him quiet."