While many retail foods come in packaging that can display evidence of possible product tampering, ice cream may not be one of them. In some brands, cartons tops can easily come off and be put back on, a bit of a design flaw that has led to a recent spate of “ice cream lickers” who flick their tongues across the flavored frozen treats and then place them back in the freezer aisle. Now, some grocery stores are fighting back.

According to Thrillist, a number of stores around the country have taken preventive measures to avoid falling victim to ice cream vandalism. Some have been locking their freezer doors and putting up signs directing customers to find an employee for assistance.

One Walmart in Corpus Christi, Texas, stationed an employee in the ice cream aisle over the July 4 holiday weekend, though it wasn’t entirely clear whether he was there for an entire shift or whether the store was staging his presence for a social media post.

The concern over tampering stems from a viral video shot at a Walmart in Lufkin, Texas that shows a woman licking a tub of Blue Bell ice cream and then putting it back on the shelf. She was later located by Lufkin police and her case was turned over to the Texas Juvenile Justice Department. Blue Bell has said that their cartons are sealed in such a way that makes tampering evident if the lid has been removed, but the company is still facing criticism for not having a seal or wrapper on its cartons.

Ice cream lickers are taking a considerable risk. Tampering with a consumer product is a crime that can carry a prison term of up to 20 years and a $10,000 fine.

[h/t Thrillist]