Currently, only 37% of McDonald’s coffee comes from a certified sustainable source, according to Bloomberg. To increase that number, the fast-food giant is partnering with the environmental group Conservation International—the same non-profit that worked with Starbucks to help the coffee chain use only “ethically sourced” coffee. Since then, Starbucks (SBUX) has verified that 99% of its coffee comes from a sustainable source.

Sustainability usually refers to farming techniques that better protect the environment, public health, human communities, and animal welfare, according to the Grace Communications Foundation.

Although the coffee industry as a whole is under pressure to adopt more sustainable farming methods, McDonald’s made the decision with customer needs in mind, according to Bloomberg.

“Our customers want to see where are products come from, what’s in it, and how it’s made,” Townsend Bailey, head of supply-chain sustainability for the Oak Brook, Illinois-based McDonald’s, told Bloomberg.

McDonald’s (MCD) didn’t say how much it will spend to make its coffee more sustainable, but it’s reportedly already spent about $6.7 million to help Guatemalan farmers learn more about difficult weather conditions and coffee-rust disease, according to Bloomberg.

“It is something that we are investing a lot in,” Bailey said. “It’s not cheap to have engagement at this scale.”

Switching to sustainable coffee is McDonald’s latest effort to provide customers better ingredients: In August, the company announced it would only use cage-free eggs and remove artificial preservatives from its chicken nuggets. CEO Steve Easterbrook inspired the change, as he works toward increasing McDonald’s sales and keep up with customer’s changing food preferences, among other things.

Fortune has reached out to McDonald’s and Conservation International and will update the story if we receive a response.