Months after finalizing her divorce from Jeff Bezos, MacKenzie Bezos has signed the Giving Pledge. The Giving Pledge initiative was launched in 2010 by Warren Buffet and Bill and Melinda Gates. It calls for the world’s richest people to dedicate a majority of their wealth to charity.

With a personal fortune of over $36 billion, MacKenzie has pledged to donate at least $17 billion to charitable causes in her lifetime. MacKenzie disclosed her new “approach to philanthropy” in a letter released on the pledge’s site.

Jeff Bezos praised his ex-wife’s decision on Twitter shortly after.