Twitter Co-Founder Evan Williams has decided to step down as a member of its board of directors, effective at the end of the month, Twitter announced in an SEC filing on Feb. 22.

Williams has served on Twitter's board for the last 12 years. Williams said in a statement, “It’s been an incredible 13 years, and I’m proud of what Twitter has accomplished during my time with the company. I will continue rooting for the team as I focus my time on other projects.”