How to run a command in the background with 'doas'?

I want to run a command in the background as root. And I have a problem with **doas** command. With **sudo**, I can use sudo --background . It will ask for password, then runs in the background. I cannot do doas & because it will ask for the password in the background and stuck there forever. I've checked the manpage but did not find the equivalent option for **doas**.