Lea Michele is keeping the memory of Cory Monteith alive.

On Monday, Lea Michele took to Twitter to remember her late Glee co-star and boyfriend Cory Monteith on what would have been his 33rd birthday.

Monteith, who died in July 2013 from a mix of heroin and alcohol, would have turned 33 on May 11. To mark the occasion, Lea Michele shared a photo and sweet message about her former love.

“I know you’re serenading everyone right now. We love you Cory! Happy Birthday..” she wrote.

Last summer, Michele and other Glee stars also paid tribute to Monteith on the anniversary of his death. “We will love you and miss you always,” the actress said.

I know you're serenading everyone right now.. We love you Cory! Happy Birthday.. pic.twitter.com/pbjMFOr06N

— Lea Michele (@msleamichele) May 11, 2015

The biggest heart and most beautiful smile.. In all of our hearts.. We love you so. Happy Birthday. pic.twitter.com/XzGVu0g5nY

— Lea Michele (@msleamichele) May 11, 2014

Other Glee stars also marked the day.

Mark Salling, took to Twitter to remember his friend and “brother.”

#MCM goes out to Cory Monteith. Miss you more than ever brother. Happy birthday http://t.co/QhB9CArkeu pic.twitter.com/QUvDCUSOic

— Mark Salling (@MarkSalling) May 11, 2015

Amber Riley, who played Mercedes, shared a photo on her Instagram with the caption, “I miss you! Gone but never ever forgotten. Happy Birthday brother.”

Lea Michele, Kevin McHale & more of the Glee cast pay tribute to Cory Monteith on his birthday http://t.co/hjaXsIMxD6 pic.twitter.com/fRvGcLvQvl

— Yahoo Celebrity UK (@YahooCelebUK) May 12, 2015

Kevin McHale posted his own touching message.

Not one day goes by…happy birthday

A photo posted by Kevin McHale (@kevinmchale) on May 11, 2015 at 11:28am PDT

Glee ended in March after six seasons.