A quick-thinking Stoneham storeowner thwarted a robbery Sunday night by throwing chili pepper in the face of the man trying to rob him at gunpoint, police said.

Saadat Khan, 49, who is no stranger to robberies – having been the victim of six in the 20 years he’s owned the C-Store on Main Street – was sweeping the floor around 9:20 p.m. when he turned to find a gun pointed in his face and a man threatening to shoot if he didn’t open the register.