Sonic Corp. has revealed a policy that restricts antibiotic use in its chicken supply.

In a press release issued on January 23, Sonic stated that its new policy, which is part of its animal welfare program, will require suppliers to refrain from using antibiotics important in human health for the purpose of growth promotion, and that antibiotics will be administered by a licensed veterinarian and only for the prevention, control or treatment of disease. The policy, which reflects Sonic’s support for the Veterinary Feed Directive rule, is effective immediately.

Sonic, which is headquartered in Oklahoma City and has about 3,500 drive-in locations across the United States, is also reviewing its policies regarding the use of antibiotics in its beef and pork supplies.

In 2016, Sonic was evaluated for its antibiotic use practices in the report, Chain Reaction 2 – How Top Restaurants Rate on Reducing Use of Antibiotics in their Meat Supply. The report took a look at the top 25 restaurants in the United States, and gave Sonic a “failing” grade. Only nine restaurants received passing grades in the report: Panera Bread, Chipotle, Chick-fil-A, Subway, McDonald’s, Wendy’s, Taco Bell, Pizza Hut and Papa John’s received passing grades.

Jack in the Box and Burger King have both since made updates to their policies on antibiotic use.