Zac Efron and his girlfriend celebrated their one-year anniversary with gushing messages on Twitter.

The 27-year-old actor took to Twitter on Monday (07.09.15), two days after their anniversary to share his love for Sami Miro.

Zac wrote: ''Happy anniversary baby :) I love you. September 5th @SamiMiro'' and although his message was late, Sami responded with ''Time flies when you're having fun. Happy anniversary baby. I love you too September 5th @ZacEfron (sic).''

Zac shared a picture of him tenderly kissing his girlfriend behind a sheer curtain while Sami posted a close-up picture of them both smiling.

Stylist and model Sami recently admitted that dating the Hollywood hunk has changed how she uses social media, particularly Instagram.

She told ''I've never spoken about us before, but, um, it's definitely different. I think that you have to take that [kind of attention] with a grain of salt... It kind of just comes with the territory, and I know there's no really changing that, so you have to just embrace it...

''I'm not trying to hide anything in my life. If I was dating someone who wasn't in the limelight, I might have more photos on [Instagram] of our relationship, but I do think it's important. I mean, it's what is going on in my life, and I think that my social media can still represent that.''