Manager Paul Kirk snapped up the 22-year-old Scot last weekend after impressing during the pre-season games.
Muir had a spell with Stirling Albion last season, but has also played in America while at university.

He was the captain of the Louisburg Hurricanes for two seasons. In 2005, he was named a 2nd team All-American in the NJCAA, and to the Division I All-Region 10 team. The list of accomplishments doesn't stop there. He was also named to the Mid-Atlantic district team. As a sophomore he took his team to the semi-finals in the NJCAA Championships and received the Region 10 Player of the Year Award, as well as being named the team MVP and before coming back to Scotland had a spell with Hartford Hawks.
"He is a real athlete, he has a great engine and keeps going and going," said Kirk. "He is a good communicator and covers his territory well. It's a chance for him to establish himself in the Irish League. Gary will train in Scotland but we will fly him each Thursday to train with us and prepare for the game on Saturday."
Kirk is looking forward to the match at Ballymena despite beginning a four match touchline ban. "It's good to see Roy Walker back in football, he has signed a few players and they will be out to impress him. We always get a tight match against Ballymena so it should be more of the same."