The Rangers defender's return to the first team at the start of February has coincided with his decision to abandon shaving, the result a magnificently bushy beard that would not look out of place in a ZZ Top tribute band.
Foster is reluctant to describe himself as a superstitious soul but, as long as he is in the team and Rangers are winning matches, his razor will be staying in the drawer.
Two significant challenges to his desire to remain hirsute will present themselves in the coming week-and-a-half. On Sunday, Rangers take on Raith Rovers in the Ramsdens Cup final, ahead of their William Hill Scottish Cup semi-final tie against Dundee United the following Saturday. Should the Ibrox club come through both undefeated, Foster's beard could be staying for quite some time.
"I don't know when I'll shave it off," he said. "I won't be shaving it off if we win on Sunday. If we win, I'll need to keep it for the Dundee United game. We'll see if it's a lucky beard or not.
"It started off because I was being a bit lazy and didn't shave. I've actually grown to like it; it's the first time I've tried growing a beard.
"I did initially think I would keep it until I scored, but I'm not committing myself to that as it could be a while. I'll leave it on for now and if we lose certain games I might shave it off.
"All players have little superstitions. I've got little things I do, but the beard is a new one. Growing a beard was never something I thought of before. We got through against Albion Rovers in the cup replay and it's stayed.
"I've got back in the team and the beard has been with me. I'm doing all right, I don't want to be like Samson - cut off my hair and lose all my powers. I'm enjoying being back in the team and we're all looking forward to a massive week."
Foster has won the Scottish Premier League title with Rangers and played in European competition with Aberdeen, but the thrill of winning trophies never diminishes, regardless of the nature of the competition. "I've played in big games," he added. "I won a league winner's medal the last time I was here, but effectively I haven't won any cups. Winning on Sunday would be right up there in terms of my achievements.
"You come to Rangers to win things and the Ramsdens Cup is no different. It would be a massive victory for the club.
"We want to finish the season on a high because it will give us something to take into next year. We all know next season in the Championship is going to be very difficult; it's a tough, tough league. We want to finish this season on as big a high as possible."
Cup football has kept Rangers focused and motivated in a season when the League One title was effectively a formality. How they fare in their next two matches will go a long way to deciding just how their campaign will be viewed.
"Being in both cups has helped," he added. "They are massive games and they've helped retain our focus. We've had a little dip in form in the league, albeit we're still winning, and I think that had to be expected. Getting back up for a cup final will be easy, because it's the chance to win silverware. We also have the chance to get to the showcase game in the Scottish season.
"These two games are very easy to get motivated for. We've been winning games and keeping the run going. It's all about momentum. You get into a habit of winning games and hopefully we can keep that going.
"We know we will have to raise our performance. We've had tough games away to East Fife, Brechin and Arbroath and we know there will need to be a marked improvement in performance. I don't think that will be a problem. You will have the enthusiasm and buzz of a cup final and the game against United a week later will take care of itself."