Surveillance video shows a man walking into the restaurant near Southfield and Outer Drive early Sunday morning.
He pulled out a handgun, made the cashier open the register and took off with an undisclosed amount of money.
The suspect is described as a white male between 5 foot 10 inches and 6 feet tall.
He was wearing a skull cap and a blue hoodie with the words 'American Original' on the back with an image of a flag and Mickey Mouse.
If you know anything, you're asked to call police at (313)943-2241, or Crime Stoppers at 1-800-SPEAK-UP. You will remain anonymous.