Former first lady Michelle Obama on Friday tweeted a note of encouragement to teenage climate change activist Greta Thunberg after President Donald Trump mocked her TIME magazine “Person of the Year” cover.

“.@GretaThunberg, don’t let anyone dim your light. Like the girls I’ve met in Vietnam and all over the world, you have so much to offer us all. Ignore the doubters and know that millions of people are cheering you on,” Obama wrote, without referencing the president or his remark.

.@GretaThunberg, don’t let anyone dim your light. Like the girls I’ve met in Vietnam and all over the world, you have so much to offer us all. Ignore the doubters and know that millions of people are cheering you on. — Michelle Obama (@MichelleObama) December 13, 2019

TIME announced on Wednesday that Thunberg, who has become the public face of climate change activism since leading school strikes in her home country of Sweden, was 2019’s winning, beating out President Trump and House Speaker Nancy Pelosi (D-CA). “I’d like to tell my grandchildren that we did everything we could,” the activist told TIME magazine. “And we did it for them and for the generations to come.”

On Thursday, President Trump called the magazine cover “So ridiculous,” and quipped: “Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!”

So ridiculous. Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill! https://t.co/M8ZtS8okzE — Donald J. Trump (@realDonaldTrump) December 12, 2019

Thunberg responded to the president’s tweet by changing her Twitter bio to read: “A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend.”

Donald Trump Jr., the president’s eldest son, ripped TIME for selecting Thunberg, arguing that the pro-democracy protests in Hong Kong should have taken the prize.

“Time leaves out the Hong Kong protesters fighting for their lives and freedoms to push a teen being used as a marketing gimmick,” Trump Jr. wrote on Twitter. “How dare you?”