Last December, Stephen Hawking warned that it could “spell the end of the human race.”

You’re reading this, so “it” hasn’t happened yet. And I don’t think it will. But who am I to argue with Professor Hawking?

“It,” by the way, is full artificial intelligence. Hawking told the BBC that it “would take off on its own, and redesign itself at an ever-increasing rate.” Eventually, it would supersede humans.

That’s a far-off worry. Hawking can fret about it for us. In the meantime, I’m concerned about another computer-related problem: investors are turning to robo-advisors and ignoring their portfolios.

Robo-advisors are a cheap tool for managing your investments. They use a series of algorithms to pick stocks and rebalance your portfolio for you. They’re supposed to make investing fun.

In my experience, investing is only fun when you make money. When you lose money, it’s not. No gadget or gizmo can change that.

So, if you want a robo-advisor to help you have this type of fun, keep these three points in mind:

1. Use your own judgment. Both humans and robots make errors. As a tool, a robo-advisor is only as good as the information you provide. Answer its questions accurately, then decide for yourself if its recommendations are right for you.

2. Don’t be penny wise and pound foolish. A good financial advisor might charge 1% of your overall portfolio to help manage your money. For a $1 million portfolio, that’s $10,000 per year, regardless of performance.

While robo-advisors aren’t free, they are less expensive.

Maybe you don’t want to pay for ongoing advice. I get it. But at least ask for help when you start using a robo-advisor. Otherwise, you might learn the true meaning of “garbage in, garbage out.”

Philip van Doorn shared a telling example of an iffy robo projection with MarketWatch: “If I stuck with the plan, I would be ‘on track’ to build a nest egg of $4.3 million by March 2047, with a required minimum annual return of 9.7%.”

9.7%? Yeah right! Sure, it might happen. But even in boom times, the conservative estimate for long-term planners was 6%.

A human can serve as the ultimate reality check. You don’t want to wake up in 2047 thinking, “I had the perfect plan. If only I’d consistently earned 9.7%.”

3. Monitor your results often. Using a robo-advisor does not mean you can set it and forget it.

Things change. The Fed’s zero-interest-rate policy was unthinkable in 2007. Then it happened. Eventually, another unthinkable market scenario will become reality. When it does, you’ll need to adjust your plan.

A robo-advisor can be a useful tool—but it’s only a tool. Just like a hammer, it needs a human to wield it.