There’s nothing like digging face first (or with knife and fork if you’re feeling fancy) into a giant slice of watermelon on a hot summer day.

A good ol’ wedge of watermelon — straight from the fridge, all juicy, sweet, and crisp — can be a serious thirst quencher when the sun is high in the sky and eating anything that’s not ice cold is out of the question.

But there's nothing worse than an unripe melon, so the best thing to do is go to your supermarket armed with the knowledge that will ensure you buy a melon that is perfectly ripe in the first place. Here’s what you need to know:

Go for uniformity. Avoid any watermelons that look lumpy, dented, or generally irregular. You want to choose one that is firm with no bruises, soft spots, or damaged areas.

Pick it up. A ripe watermelon will feel heavier than one that is less ripe. This extra weight is a great indicator that it is full of water (not dry and flavorless). Compare different watermelons that are roughly the same size and select the heaviest one — it will also be the ripest.

Find the field spot. This is the yellow spot that you will see on one side of the watermelon. It indicates where the melon sat on the ground as it was growing and ripening. The yellower the spot is, the riper the watermelon is going to be. Definitely avoid a watermelon whose field spot is very pale, white, or not there at all — this means that is was picked far too early and is not at all ripe.

Give it a knock. This is a pretty well-known technique than many watermelon-lovers swear by. Simply knock on your selected melon with your knuckles and take note of how it sounds. A deep, dull sound indicates that the fruit is not quite ripe; a deep, hollow sound, however, is just what you are listening for.

So there you have it: some simple tips that will help you source a perfect watermelon to enjoy whenever a watermelon craving strikes. Never succumb to a subpar piece of watermelon again. Instead, browse the fruit section with savviness, and always buy whole fruit rather than cut.

This article originally appeared on The Daily Meal.