Zachary Quinto is ''grateful'' after four years of sobriety.

The 42-year-old star - who has been honest about his struggles with addiction - celebrated the milestone on Sunday (24.05.20) as he shared shirtless selfie and commented on the significant moment.

Taking to social media, he wrote on Instagram: ''Four years sober sun-kissed selfie. Grateful for today!''

The 'Star Trek' actor made a similar post this time last year as he revealed he was ''working every day to honour and realise his full potential''.

He wrote at the time: ''Three years sober today. i guess i wore the right jumper for the occasion. when i think about how far i've come and how much i've grown and how much more i love myself... i'm really blown away.

''very far from perfect - but perfectly flawed. and working every day to honour and realise my full potential. three years ago i had lost a connection to gratitude almost entirely.

''today i am brimming with it. for this touchstone. for life's abundance. for true friends. for support. for the sweet freedom of this journey. may it continue with compassion - curiosity - honesty and above all... LOVE (sic)''

Zachary has also revealed how he hopes being candid about his sobriety will help others with their own journeys.

He said: ''I was really proud of that [sobriety] accomplishment for myself and to share my experience and to encourage other people who are interested in that journey for themselves is something that I have a real privilege to be able to do.

''I felt like it was a moment where I wanted to take that opportunity and just acknowledge that my experience of life is entirely different now than it was three years ago, and I couldn't be more grateful and happier for that. Huge gratitude.''