Former President Barack Obama cracked a joke Tuesday about his place of birth at the opening of the inaugural Obama Foundation Summit in Chicago.

"The reason I’m so excited to see you all here today in part is because this is were I started,” Obama said, who got his start as a community organizer in Chicago.

“Now this isn’t where I was born. I was born in Kenya. That’s a joke," he quipped amid laughter, before adding that he was born in Hawaii.

The joke references a tenet of the so-called "birther" movement, which during his presidency questioned Obama's U.S. citizenship and for years had an advocate in President Trump. However, Trump admitted during the presidential campaign in September 2016 that Obama was born in the U.S.

Obama, who released copies of a short-form "certification of live birth" in 2008 and a long-form birth certificate in 2011 in an effort to silence the rumors, has since reacted to the "birther" movement in good humor, telling jokes about it over the years. Notably, while he was visiting Kenya in 2015 he made a joke about his birth certificate. "I suspect that some of my critics back home are suspecting that I'm back here to look for my birth certificate," Obama said during a toast at a state dinner. "That is not the case."

The two-day summit in Chicago, which aims to motivate civic leaders of the future, is one of Obama's post-presidency projects. The Obama Foundation is raising money for the Barack Obama Presidential Center in Chicago’s South Side.

Prince Harry of the United Kingdom also spoke at the event on Tuesday. Former first lady Michelle Obama is slated to speak on Wednesday, along with Caroline Kennedy and "Hamilton" creator Lin-Manuel Miranda. Obama is expected to speak again in the late afternoon as the summit winds down, before a concert with Chance the Rapper.