California’s Bureau of Cannabis Control has recently unveiled new regulatory rules that will ban drones from delivering marijuana, The Verge says.

The Bureau is currently developing regulation surrounding weed use and sales under the Medicinal and Adult-Use Cannabis Regulation and Safety Act (MAUCRSA) after recreational marijuana was legalized in California.

“Cannabis goods will be required to be transported inside commercial vehicles or trailers,” the proposed program description reads.

“Transportation may not be done by aircraft, watercraft, rail, drones, human powered vehicles, or unmanned vehicles.”

Under the rules, deliveries can only be made by licensed retailers, “in person by enclosed motor vehicle,” and the vehicles used for deliveries must have a GPS that allows the seller to track the package. The Bureau also specifically states that those delivering the cannabis aren’t allowed to consume the substance while out on the delivery.

California is the largest economy in the US and the legal marijuana industry could be worth $5 billion to the state. Licenses for cannabis distributors, retailers, testing labs, and other businesses will be issued beginning January 1, 2018.