When Mozilla named JavaScript inventor Brendan Eich as its new (and short-lived) CEO, it left the CTO position Eich previously occupied unfilled. Today, Mozilla announced that Andreas Gal will become its new CTO. Most recently, he was Mozilla’s Director of Research and later VP of Mobile and Research.

Gal, who joined Mozilla six years ago, brings an impressive resume to the job. At Mozilla, he worked on many of the core technologies behind Firefox, including its Tracemonkey just-in-time JavaScript compiler, and co-founded projects like PDF.js, the HTML5 Flash player Shumway and Firefox for Android. He also played a crucial role in the Firefox OS project, which he essentially co-founded back when it was still called Boot to Gecko.

Gal also worked on Rust and Servo, Mozilla’s new programming language and the core of what could become the next generation of its browser engine.

In his own announcement, Gal notes that he believes that “we are on the cusp of the same open web revolution happening in mobile, as well, and Mozilla’s goal is to accelerate the advance of mobile by tirelessly pushing the boundaries of what’s possible with the Web.”

It’s no surprise Gal puts this much emphasis on mobile — an area Mozilla was slow to embrace. According to Mozilla’s interim CEO Chris Beard, Gal will remain Mozilla’s VP of Mobile “as we continue to focus our efforts on delivering and scaling Firefox OS.”