You don’t want to sell Vanguard GNMA. I know its price is down. And often, when investors see share prices go down, they sell. They follow the herd. Resisting that impulse isn’t easy.

But the herd forgets that stocks were slaughtered in 2008 while GNMA was a port in the storm. You can bet there will be another stock market crash as bad as or worse than 2008. It’s really just a matter of when.

2008 wasn’t a bloodbath for everyone. The average GNMA fund tracked by Morningstar was up 6.6%. It was a terrific year. Unfortunately, it seems you can count on one hand the lucky few who stuck around with their boring GNMA position and didn’t get greedy leading up to 2008.

Investors, not you of course, pulled money out of GNMA funds for five consecutive years, from 2003 to 2007, according to Morningstar. This was when GNMA funds yielded a mouthwatering 5%. But investors were giddy about the stock market. Sure, they took a beating with Internet stocks in 2000, but now it was time to make up for those losses and ride that market into the sunset, where retirement dreams come true—until they don’t.

It’s hard for investors today to get excited about a 2.3% yield—I get it. But that’s the reality of the day. Relatively speaking, it’s a whole lot more than the 0.14% yield for the Vanguard Short-Term Treasury fund. You need to find income where you can.

Think about your GNMA fund as you would a piece of income property. For a landlord, it’s a waste of time to worry about the price you could get for the property from month to month. The monthly rents are what pay the bills. GNMA is your triple-decker. Why sell it? You need the rent money.

You shouldn’t be alarmed about a fund with an average duration of 4.3 years and explicit backing by the government. I still view prepayment risk—the risk of a mortgage being refinanced or prepaid and replaced with a lower-yielding mortgage at a lower rate—as low. You still need a credit score near 800 and a dump truck full of cash to do a refinancing, and the Fed’s going to do everything in its power to prevent dislocation in mortgage-backed securities, announcing last week that it might hold mortgage-backed securities until maturity. The waters may be choppy with Vanguard GNMA, but it’s an anchor to windward that you may need to fall back on someday.