Quintin Packer was not about to see his prized Christmas present - a bike from his parents - get stolen right in front of his eyes.
So when he spotted a young man armed with bolt cutters attempting to cut the chain from his bike outside a Kerikeri supermarket, he knew he had to act.
"I was panicking and I didn't [know] what to do, so I decided to hit him with my helmet."
The 12-year-old from Kerikeri was with a group of friends last Friday when the incident happened about 4.30pm.
They had just ordered a pizza at the Pizza Hut around the corner when Quintin walked towards the New World supermarket, off Kerikeri Rd, to get his bike.
He spotted the man - wearing a hooded sweatshirt and with the hood up - trying to make off with the bicycle. The man was in his late teens to early 20s.
"[I thought]: 'Gosh, is my bike going to get stolen? Once I hit him, I was expecting him to fight back. I was glad when he ran away."
Quintin's father, Jamil King, said he had spoken with his son about the incident and was grateful the alleged offender did not turn around to retaliate.
"I think the guy got a hell of a fright because [Quintin said] he just jumped up and just bolted.
"Quintin didn't say anything. He just went straight up to him because he saw that he had bolt cutters in his hands. He was trying to cut the chain off."
The family has since made a report to police, who are investigating the incident.
CCTV security footage from the area has also been passed on to authorities.
A police spokeswoman confirmed that a complaint had been received regarding a 12-year-old boy witnessing a male trying to steal his bicycle outside a supermarket on Friday.
"The boy hit the suspect with a helmet and, as a result, he ran away.
"Police encourage members of the public - especially children - not to take the law into their own hands. If you witness someone attempting to take your property, call the police immediately on 111.''
Despite that, Quintin's dad said he was proud of his son's alertness.
"He saw a situation and straight away - focused. He didn't just go into shock and stand there," King said.
"I always say to be alert and focused because you never know what could happen."
Quintin had a message for anyone who might find themselves in similar circumstances.
"If you're ever in this situation, you need to make sure they are trying to steal your stuff before you act. Don't be afraid to stand up for yourself.''
And, he also had a few words for the would-be thief: "What causes you to want to steal other people's stuff?''