Impulse buys can be detrimental for a couple of reasons. They can prevent you from getting the things you really want (such as a down payment on a house, some other larger purchase you’d like to make, or getting out of debt).

This is especially likely to happen if you’re a frequent impulse buyer. A few extra outfits that looked cute at the time but then sat in the back of your closet could have paid for a longed-for trip out of town.

Impulse buys can also involve additional long-term costs that you probably didn’t realize would come along for the ride. For example, if you impulse buy a car, you’re probably not aware of just how much it will increase your insurance, registration costs, or even gas. If you impulse buy a phone or some other item that comes with a monthly plan, you’re probably not accounting for the long term effect that will have on your money. Or heck, even if you impulse buy a shirt, you might discover that you have nothing to wear with it, and end up buying a pair of pants to go along with it.

Don’t get me wrong — I don’t think there’s anything wrong with buying the things you really want or need. It’s just that impulse buys can prevent you from doing exactly that.

To prevent impulse buys, ask yourself one little question:

Did I want this exact thing before I saw it just now?

If the answer is no, it’s an impulse buy. That’s the point at which you turn around and leave the store. Make a note of where you saw it if you think you might still want it later. (You probably won’t.) It doesn’t matter if it’s a good deal — if you didn’t want it before you saw it, you probably don’t really want it. Your emotions (and the store’s marketing efforts) are just urging you to buy.

Remember what you really want instead.