North Korean leader Kim Jong Un cracked a smile after overhearing his older Russian and Chinese counterparts chat about living forever at Wednesday’s military parade in Beijing, a conversation that has made global headlines after being captured on a hot mic.

While walking toward the viewing stand, Xi Jinping remarked to Vladimir Putin that 70 is “still a child’s age” and that people might live to 150 this century. Both leaders are 72 years old.

Putin, speaking through an interpreter, said that thanks to medical advances like organ transplants humans could even achieve “immortality,” according to Chinese state media