Star Trek actor Leonard Nimoy has revealed that is suffering from lung disease.
The 82-year-old wrote on Twitter that despite stopping smoking 30 years ago he had developed chronic obstructive pulmonary disease.
He urged his 808,000 followers to "quit now".
Nimoy last appeared on screen in 2013 in Star Trek Into Darkness, reprising Mr Spock, the Vulcan character he has played since 1966.
He was the only actor from the original series to be given a role in the reboot of Star Trek, playing cameo parts as the elder Spock.
The actor has also been a great supporter of director JJ Abrams' vision for the new films and his ability to win over new audiences.
As well as starring as Spock in the original Star Trek series, he also directed two of the franchise's films - Search for Spock and Voyage Home.
He also made a number of guest appearances in science fiction series Fringe, which ran until 2012.
Nimoy was recently photographed being pushed in a wheelchair at a New York hospital, attached to breathing apparatus.
Chronic obstructive pulmonary disease (COPD) is an umbrella term for a number of illnesses including emphysema and chronic bronchitis, and affects millions of people around the world.
It damages air sacs and passages to the lungs, and can make breathing a struggle. The majority of cases are caused by cigarette smoke.