The former England international goalkeeper believes the club's owners must ensure the Sweden international defender remains at the Hawthorns with his contract soon to expire
The 29-year-old has made 141 appearances for The Baggies, scoring 11 times since his arrival from NEC Nijmegan in 2008, but is set to become a free agent next summer after failing to agree an extension to his stay in the west Midlands.
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|12/1||Jonas Olsson is 12/1 with William Hill to score at anytime for West Brom against QPR on Saturday
But the former England international stopper is keen to keep the highly-rated Olsson and hopes he will pledge his long-term future to the club in order to fend off mounting interest in his services.
"The chairman needs to lock him in a room and hopefully get something sorted out," Foster said.
"If you take everything into account I'd much rather be playing with him and Gareth McAuley than the majority of defensive pairings.
"It's people like Jonas we need to be keeping. He is such an important part of our team."
West Brom have suffered just one defeat in the Premier League this season, a 3-0 reverse against Fulham at Craven Cottage.
Steve Clarke's men welcome struggling QPR to the Hawthorns on Saturday, after Darren Bent rescued a late point for Villa to cancel out Shane Long's opener last Sunday.