Future-of-food startup Soylent is cautioning customers to avoid eating its new snack bars amid reports they were making people sick, the company announced Wednesday.

“It has recently come to our attention that a small number of our customers have experienced gastrointestinal issues after consuming Soylent Bars,” reads a statement on Soylent’s website. “As a precautionary measure, we are halting all Soylent Bar purchases and shipments and are advising our customers to discard any remaining bars in their possession.”

Customers who already received their snack bars are entitled to a refund, Soylent says.

Soylent, known for its pre-mixed drinks and powders meant to replace traditional meals, began selling the snack bar about a month ago. “With only 250 calories, Soylent Bar makes an excellent snack or small meal,” reads Soylent’s description of the Soylent Bar. “Our newest product offers the same complete nutrition, but in a lighter, more portable form factor. Soylent Bar provides one eighth of an average adult’s recommended dietary needs.”

The issue may increase skepticism of Soylent’s other offerings, though they are not affected by the recall.

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Write to Alex Fitzpatrick at alex.fitzpatrick@time.com.