Glasgow have handed new deals to hookers Pat MacArthur and Fraser Brown, Warriors have announced.
The duo have signed two-year contracts at Scotstoun until at least May 2018 and follow captain Jonny Gray and fly-half Finn Russell in committing their futures to the Guinness Pro12 champions.
MacArthur, capped six times for Scotland, joined Glasgow from Ayr in 2007 and the 28-year-old has gone on to make 126 appearances for the club.
He said: "I've really enjoyed my eight years at the club and it was an easy decision to stay at Scotstoun.
"There is a fantastic culture here at the Warriors and everybody wants to work hard to improve themselves and the club.
"Everything about the Warriors has grown since I joined and I'm really excited about the future."
Brown joined Glasgow from Edinburgh in 2013 and has made 36 appearances for the club.
The 26-year-old, who was included in the Scotland Rugby World Cup squad, has 15 caps for his country.
He said: "I feel I've really developed as a player since joining Glasgow and I'm enjoying my rugby.
"I've gone on to represent my country and playing at the Rugby World Cup was a huge honour.
"Winning the Pro12 last season was one of the highlights of my career and I'm really looking forward to the next two seasons at Scotstoun."
Head coach Gregor Townsend added: "We're delighted that Pat and Fraser are staying with us for another couple of years.
"They have both worked really hard to improve aspects of their game and, along with our other hookers, compete hard for the starting jersey."