On Boxing Day, Marc-André Delisle was crossing Brunswick Boulevard near Fairview Mall in Pointe-Claire, as he head over to an office supply store.
But something caught his eye on the way.
"I saw envelope on the ground with an amount on it, so obviously I took a look at it," he said.
On Wednesday, Delisle took to the West Island Community Facebook page to try finding out more information.
He also wrote in his post that he wants the owner to tell him the exact amount and the bank it comes from.
So far, he's had no luck in finding the owner, but people on Facebook are trying to help, too.
"I've got a lot of people calling me or messaging me, trying to figure out if it was theirs, but besides that I haven't had any luck so far," Delisle said.
Delisle is exploring options of what he will do with the money if the owner does not turn up, but keeping it is not one of them.
"It's probably someone's pay or vacation pay or Boxing Day money that they got on Christmas," he said.
Delisle said he will either give the police the envelope or donate the money to a local dog shelter.
Anyone with information is encouraged to reach out to him on Facebook.
-CJAD 800's Alyssia Rubertucci contributed to this report.