Elon Musk is not alone in worrying a bit about artificial intelligence: Microsoft founder Bill Gates revealed in a recent “ask me anything” session on the popular sharing site Reddit that he was also concerned about the implications of super intelligence.

Gates said machines that do jobs for us and aren’t super intelligent would be quite beneficial if it is correctly managed, but in a few decades when AI becomes particularly advanced, he said he agrees with Musk — who founded Tesla and SpaceX — and he doesn’t understand why more people aren’t concerned, according to a PC Magazine report.

Still, there are some benefits in working with AI, and it can still be used in a beneficial way if used carefully, he said.

Microsoft itself is working on what he calls a “Personal Agent,” which will remember everything you need to know and help you prioritize what needs to be done.

He called bitcoins “exciting new technology,” but noted that he’s approaching the digital cautiously. For example, poor people shouldn’t use bitcoins because of how wildly its value fluctuates compared to local currency. Also, its anonymity creates problems when you need to reverse a transaction that was a mistake. Finally, it has the potential to help terrorists, he noted.

Gates answered a number of questions during the chat, ranging from his work in charity in helping developing nations ward off disease to relatively inane questions about his personal life.

He said that languages make him feel “pretty stupid” because he doesn’t know any beyond English. He said he wished he knew French, Arabic, or Chinese, and pointed out that Facebook founder Mark Zuckerberg once performed an entire question-and-answer session in Beijing in Mandarin.