A machete-wielding robber raided five Greggs bakeries, threatening staff and stealing cash, police say.
The robber wrapped the weapon in a plastic bag and targeted the Birmingham shops as they opened.
Branches in Ward End, Weoley Castle, Druids Heath, Acocks Green and Erdington were raided between February and July.
A 40-year-old man from Sparkbrook has been arrested on suspicion of robbery, West Midlands Police said.
Det Con Laura Halpin said: "We've linked at least five robberies at Greggs shops where an offender has struck at opening time and threatened staff with a machete wrapped in a plastic bag before making off with cash.
"No-one was hurt but clearly these were traumatic incidents for the staff who were faced with an armed man and threatened with violence."
A machete was recovered during Tuesday morning's raid in Sparkbrook, she added.