A limp penis isn’t just bad news for your sex life: Guys with erectile dysfunction have a 70 percent increased risk for premature death, a new study from The University of Mississippi finds.

Poor cardiovascular health is the most common cause of ED, said Dr. Tobias Köhler, an associate professor of urology at the Southern Illinois University School of Medicine. So if you’re unable to get hard, it’s often an early sign that your heart is in trouble.

In fact, many guys whose ED is caused by poor cardiovascular health wind up having life-threatening heart problems like a heart attack in the next five years, Köhler said.

The vessels that carry blood to your penis are tiny, only one to two millimeters across, so they get clogged easily, Köhler said.

If plaque starts to build up in your vessels—thanks to a poor diet, a lack of exercise, smoking, age, or genetics—the blood flow to your penis is the first thing that will get blocked off, Köhler said.

That can make it impossible to get an erection.

Related: How to Keep Your Penis Healthy

If the plaque continues to build, it will start affecting larger arteries, like the ones that carry blood to and from your heart. That can cause a heart attack or sudden death, he said.

That’s why it’s crucial to get your ED checked out by a doctor. If you heed the early warning sign, you may be able to fix your cardiovascular problems before they become fatal.

If you’ve been consistently unable to get it up, or keep it up, for three months, make an appointment with your primary physician, said Köhler.

Tell your doc about your erection problems—and make it the first thing you bring up, so your doctor has time to thoroughly check you out, he said.

(When your erection is up and running again, use this master course on How to Pleasure a Woman to have the best sex of your life!)

If blocked arteries turn out to be the culprit, an improved diet and exercise regimen may reverse the damage and get your penis back in working order, he said. Your physician may also give you an ED drug like Viagra to help your sex life in the meantime.

This article originally appeared on MensHealth.com.