"Louis has been a stalwart for the club this season. He has played a good number of games and now we have extended his deal," City boss Gary Johnson told the club's official website. "He has captained a promotion-winning side and he has been rewarded for that.
"Jamie came here on a lower wage and I told him when he signed that if he could get himself in the first-team regularly, then we would sort out his contract.
"He responded in the best possible way by trusting my word and becoming player of the season. He fully deserves this new deal."