The owner of a noodle shop in China has admitted to using poppy seeds in his noodles to keep customers coming back to his restaurant.

Liu Juyou, a customer at the restaurant in Yan'an in the Shaanxi province, made the discovery after he tested positive for drugs during a routine traffic stop — despite the fact that he says he has never taken drugs in his life. Juyou suspected the restaurant's food was behind his test results, since he had eaten there mere hours before.

To confirm his suspicion, Juyou asked some of his relatives to eat at the shop and then drug-test themselves, and as it turns out, their urine tested positive for drugs, too.

The store's owner, identified as Zhang, confessed to the Xi'an Evening News that he had crushed poppy buds into powder and added it in with the seasoning to his noodles. The result, as the BBC notes, was "opium-laced noodles."

Police reports stated that the unprocessed seeds contained enough opiates to cause positive drug-test results and could "produce dependence" in consumers. Zhang was detained for 10 days by the police.

The South China Morning Post notes that poppy seeds were once an ingredient in Chinese hot pot sauces, but their use was banned. Meghan DeMaria