Imagine the frustration of staying at a Hyatt Category 3 property and accidentally paying for it with a Category 1-7 free night certificate — all while a Category 1-4 free night certificate sits in your account. Ouch.

This experience taught me about a World of Hyatt quirk you should know. Here’s how to ensure Hyatt pulls the right certificate from your account.

World of Hyatt issues two free night awards: Category 1-4 free night awards and Category 1-7 free night awards.

The former can be used at any property rated in categories 1-4 on Hyatt’s award chart. These aren’t affected by Hyatt’s peak and off-peak pricing, either. As long as you can find a standard award room at an eligible property, you can use this certificate there.

You can earn these free nights in the following ways:

Category 1-7 free night awards are more valuable, allowing you to use them at Hyatt properties in categories 1-7 and all-inclusive properties in categories A-D.

These awards also are more difficult to earn. You’ll need 60 qualifying nights with Hyatt in a year to earn a Category 1-7 certificate, also qualifying you for top-tier Globalist status.

Related: The 12 hotels where you’ll get the most out of your Hyatt reward night certificate

Pulling the right certificate

If you have both types of awards in your account, you don’t want to use a Category 1-7 award when staying at a hotel in Categories 1-4. Unfortunately, I did that without realizing it on a short-notice booking at the Grand Hyatt Incheon.

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When booking a hotel online and using a free night award, Hyatt’s website automatically pulls the award that expires first. You don’t have the option to choose the lower-value award.

To get around this, call World of Hyatt reservations at 1-800-544-9288, or contact your My Hyatt Concierge (if you have one).

Related: Quick Points: How and why you should regularly audit your loyalty accounts