Butter produced by the Fresno State Creamery and sold mostly through the university’s Gibson Farm Market is being voluntarily recalled because of possible contamination of a bacteria called listeria monocytogenes.

The recall includes 15-ounce tubs of the “regular” butter spread stamped with the product code 249 and a sell-by date of either “02/01/20” or “08/01/20,” the university reported Wednesday afternoon. Forty containers of the butter were sold at the farm market at the college, and one additional tub was sold at another site.

The university is asking customers who bought the butter product at the Gibson Farm Market to return products with the affected code and sell-by states to the store for a refund. So far, no illness have been reported from consuming the product, but the creamery is recalling the butter voluntarily as a precaution.