Your bank has your number.

Credit and debit card fraud alerts are up 15% from two years ago, according to data released Friday by CreditCards.com. Three in 10 Americans had received at least one fraud alert regarding a credit card and one in four had gotten one about a debit card.

What’s with the uptick in fraud alerts? “I think it’s up due to an abundance of caution,” says Matt Schulz, CreditCards.com’s senior industry analyst. “Fraud continues to grow, especially online fraud, and banks are doing everything they can to knock that down; this is one of those tools.” Fraud alerts are typically triggered when a purchase for something out of the norm for that person gets made.

If you’re affluent, you’re much more likely to have gotten a fraud alert. Nearly seven in 10 (68%) of those with annual household income of $75,000 or more have received a fraud alert, versus just 40% of those with income between $30,000-$49,999 and 26% with income under $30,000.

Schulz says this may be due to a variety of things. More affluent consumers tend to be very valuable to banks, so they may be extra cautious with them, and because the affluent often have higher limits on their cards, their getting hacked can be more costly to banks. Plus, the rich tend to be targeted by fraudsters more. And they are likely to travel and make very large purchases more — both of which are more likely to trigger fraud alerts. — even when totally legit. (About one in three people who got a fraud alerts said it was because of a legit purchase they made.)

No matter your income, no one wants fraudulent purchases on their card. And while there’s no foolproof way to protect yourself, there are a few things you can do. One of the biggest: beware of who you give your credit or debit card information to, says Schulz. If you get an email asking for your card information for something, even if it seems legit, call the company directly (look up their number on their website, don’t use the one provided in the email) to ask if they sent the email, for example.

You should also watch where you shop. Fraudsters often set up websites that look legit but in fact may be fronts to sell you stolen goods and steal your credit card information, as Moneyish reported this week. Forter CEO Michael Reitblat says that the signs a site isn’t legit are often subtle, like in this fictional example: If a retailer’s name was Hill and its legit site was Hill.com, the fraudulent site might add and “s” to the end of that. Unsure if a site is legit? this useful browser extension can give you an overview of a site, as well as reviews and traffic.

Want more tips for protecting your cards? Check out this Wall Street Journal guide.