Better stock up on wine and spirits just to be safe - the union representing Ontario's 6,000 liquor store workers is calling for a strike vote later this month to pressure the provincial government.

The Ontario Public Service Employees Union will hold the vote between May 20 and 22, but pledges to immediately return to the bargaining table.

The union accuses the Liquor Control Board of Ontario (LCBO) of replacing permanent jobs with lower-paid casual positions that have no benefits or guaranteed hours.

Sixty per cent of LCBO workers earn less than $20,800 annually, the union added in a Friday statement.

OPSEU's collective agreement with the LCBO expired on March 31.