Star Trek‘s original Spock, Leonard Nimoy, tweeted Thursday that fans should stop smoking now. Nimoy revealed that he has COPD on Jan. 29 after worried fans asked about a photo taken of him in which he’s in a wheelchair wearing an oxygen mask.

COPD is a chronic respiratory disease caused by smoking that has no cure. Since opening up about his disease, Nimoy has encouraged followers on social media to stop smoking as soon as possible so as not to suffer the consequences later.

Nimoy ends all of his tweets with “LLAP” or “live long and prosper,” his character’s catchphrase from the Star Trek series.