The Flames announced the move Saturday, a day after longtime Flames goalie Miikka Kiprusoff played what some are speculating as the final home game of his career with the club.
The Flames acquired MacDonald off waivers from the Detroit Red Wings on Feb. 11 while Kiprusoff was missing time due to injury.
MacDonald's 7-7-1 in 18 games this year with Calgary. He registered a 2.91 goals-against average and a .900 save percentage.
He has appeared in 119 career NHL games with Boston, Detroit, New York Islanders, Toronto and Calgary.
On Friday night Kiprusoff made 32 saves in a 3-1 victory over the Anaheim Ducks. It was his second straight impressive start in a rough season where he has a 3.41 goals-against average and .882 save percentage.
Many expect the 36-year-old, who refused to waive his no-movement clause at this year's NHL trade deadline, to retire in the off-season.
Calgary, which is set to miss the playoffs for the fourth straight season, has four games remaining — all on the road.