Elon Musk has big plans for his infrastructure venture, The Boring Company. The tech mogul has touted that the tunnels burrowed by his company could lay the foundation for a cross-country hyperloop transit system. And on Tuesday, the CEO hinted at the next city that could be getting the hyperloop treatment.

The Boring Company already plans to open a two-mile proof-of-concept tunnel that connects SpaceX’s Hawthorne, California headquarters to a Los Angeles suburb on December 10. After that, the company might look northward for its next California-based tunneling effort, to San Francisco.

This is all based on an admittedly brief online exchange between Musk and fellow tech entrepreneur Marc Benioff, the CEO of cloud-based software company Salesforce. In response to the teaser footage of the LA tunnel Musk shared on Tuesday, Benioff asked him to expand his transit tunnels to the Bay Area.

“Elon can you and [The Boring Company] help us in San Francisco? We will have a cool new transit center soon, but we need rapid transportation from Downtown to the Ocean, Marin Country, East Bay, San Jose, and LA,” he wrote. “Bullet train too far away! Can you do it?”

“Sure, we can do it,” the chipper Musk dropped in the replies.

As it stands, The Boring Company has been green-lit to start burrowing under Chicago, Washington D.C., and has laid out a blueprint for expanding its LA tunnel. Somewhat surprisingly, San Francisco hasn’t been part of the equation, at least publicly, until now.

Musk has described that he envisions the LA transit system as an underground network of tunnels that serves automobiles, buses, cyclists, and pedestrians. Instead of a car-centric underground highway he wants to prioritize foot, bicycle, and public transit traffic.

How Elon Musk envisions the LA transit system.

This could be especially helpful in the Bay Area, which has not only has a booming population, but the transportation growing pains that come with it, case in point its high cyclist fatality rates.

San Jose and San Francisco actually have the fifth and seventh highest cyclist fatality rates per million people in the U.S., according to a 2015 report by the National Highway Traffic Safety Administration. Lots of those people were probably bike commuters: Last year, more than 44,000 bikes were counted on an average weekday in San Francisco, according to the San Francisco Municipal Transportation Agency.

No concrete plans seem to have been drafted about expanding The Boring Company’s reach to the Bay Area, so far, just Musk’s informal Twitter response. But of course, Musk has been known to try and act on his Twitter promises in the past, and not always the trivial ones like his plan to hawk flamethrowers.

Photos via The Boring Company