No matter how many security enhancements are made to Canadian banknotes, counterfeiters always seem to find a way to keep their bills circulating.

One Toronto-area resident learned that lesson the hard way – and now he’s warning others about his experience so they won’t suffer the losses he did.

Michael Boddy of Richmond Hill, Ont., says he unknowingly accepted 63 fake $20 bills from somebody who had agreed to buy a high-end iPhone he was selling.

It was dark out, he told CTV Toronto, but the bills looked and felt the way he would expect real $20s to feel – so he left without realizing anything was amiss.

It was only once Boddy returned to his home and examined the notes more closely that he started to suspect he’d been duped.

“[I] started looking at it a little bit more and thinking ‘This just doesn’t seem right,’” he said.

The bills’ material didn’t have quite the same feel as the polymer of official currency. Some of the raised ink was missing. And many of the notes contained duplicate serial numbers.

“Be careful selling your stuff, because there are crooks trying to get your stuff for free,” Boddy said.

According to RCMP statistics, the number of counterfeit bills being passed in Canada has been rising since 2015, when the number of fake bills detected was at a long-term low.

Fake $20 bills circulating in British Columbia’s Fraser Valley made headlines last spring. Around the same time, police in London, Ont., received dozens of reports of fake $100 bills making their way around that city.

The Bank of Canada includes new security measures on each new series of banknotes it creates.

The central bank provides free public training guides on how to detect counterfeit bills.

In general, for most newer-series banknotes, it recommends checking for difficult-to-counterfeit features such as a hologram in the otherwise transparent window of the bill, raised ink in places including the phrase “Bank of Canada,” and a transparent outline around the maple leaf on the face side of the bill.

The new vertical $10 bills have raised ink on the portrait, large number 10 and the word “Canada,” as well as a picture of an eagle feather which changes colour from gold to green based on the angle it is being viewed at.

There were approximately 8,000 counterfeit notes detected in each of the first three quarters of 2018, with $100 and $20 denominations being the most common.