Google has acknowledged that the best time to be on your computer might not be while you're driving.
The company updated its terms of service this week and the new guidelines add a note of caution about road safety.
"Some of our services are available on mobile devices," the updated terms say. "Do not use such services in a way that distracts you and prevents you from obeying traffic or safety laws."
Questions about the legality of driving with Google Glass were raised last month when a California woman was ticketed for driving while wearing the head-mounted computer system.
In addition to speeding, the ticket included the violation, "Driving with monitor visible to driver (Google Glass)," which the driver posted on her Google+ page.
Google declined to say on Friday if its updated terms are referring specifically to Glass.
Whether Glass can be used while driving or bicycling depends on where you are and how you're using it, Google says on its Glass FAQ page.
"Whether or not any laws limit your use of Glass, always be careful," the company said.
Most states have passed laws limiting the use of mobile devices while driving a motor vehicle. In California, a portion of the Vehicular Code states that people can't drive if a display screen showing content for entertainment or "business" purposes is operating in front of the driver's seat.
Google appears to have given thought to Glass' safety in some pretty specific other situations too. While operating a jackhammer, "use caution," Google says on the FAQ site.
As for scuba diving? "Uhhh... no," Google says. Liquids and glass do not go well together.
(Martyn Williams in San Francisco contributed to this report.)