McDonald’s is selling a lot more burgers. The company announced this week that it sold 40 million more Quarter Pounders in the first quarter of 2019 compared to a year earlier. That’s a 30% spike. 

The fast food giant credits its rising burger sales to a major supply chain switch. Last May, it switched from serving frozen to fresh beef patties. 

Analysts say the move was no cheap endeavor and took years of preparation to pull off. Franchisees had to add new refrigerators and adjust cooking temperatures to meet food safety laws. Suppliers had to make sure they had enough fresh beef available, as well as changing packaging and delivery methods.

McDonald’s has embraced fresh beef to better compete with rivals like Wendy’s and Burger King.