One of the lesser-known ways to use Marriott Bonvoy points is transferring them to dozens of airline partners.

Yes, dozens.

On a normal day, Marriott offers transfers to the majority of these partners at a 3:1 ratio. So, transfer 60,000 Marriott points to an airline partner and receive 20,000 miles or points. But for a limited time, one of those partners is getting a boost.

Through October 31, Air Canada is advertising the “only chance this year” to snag a 15% bonus on Marriott Bonvoy point transfers to Aeroplan.

60,000 Marriott Points Become 28,750 Aeroplan Points

This month only, Marriott Bonvoy point transfers to Aeroplan are 15% more rewarding.

Here’s how it works. Aeroplan will add 15% more points to an account after a transfer from Marriott Bonvoy. And there’s already a 5,000-point bonus for every 60,000 Marriott points transferred.

In other words, transferring 60,000 Marriott points to Aeroplan at the standard 3:1 ratio nets 20,000 Aeroplan points. The 5,000-point bonus brings that total to 25,000, and then the 15% transfer bonus gets tacked on top.

So, transfer 60,000 Marriott points to Aeroplan during October and the final total is 28,750 Aeroplan points.

Program members can transfer up to 240,000 Marriott points per day, and the bonus points may take between eight and 10 weeks to land in an account.

To transfer, click here and log in to your Marriott Bonvoy account.

Generally speaking, the 3:1 transfer ratio should at least give some pause before automatically transferring Marriott points, especially without a specific use in mind. But even without a transfer bonus on the table, these Marriott conversions offer a backdoor way to earn more airline miles.

It just so happens that transferring to one particular partner is a little more rewarding this month.