Calgarian Jeremy Ensign had just finished paying for a tank of gas on August 13 when a piece of plastic fell off the pump's card reader.
He called police, who confirmed the object was actually a card skimming device.
“When I saw the chip and wires I knew right away…I was pretty choked, but what can you do?” Ensign told Metro News.
He shared photos of the skimmer on social media to warn others.
The skimmer was found at a Husky gas station. Husky confirmed to CBC News that it is cooperating with police on the investigation.
Card skimmers can be difficult to spot. Often, skimmers perfectly duplicate a card reader on an ATM or gas pump, making it easy for people to duplicate credit card information.
Calgary police said it's important to take a good look at card readers to avoid fraud.
“You want to look for any type of tampering, any anomalies, any abnormalities, anything that appears broken. You’re looking for loose bolts. You’re looking for plastic coverings over the PIN pad itself," Det. Dean Nichol told CTV News.