Ryan Gosling helped a fan propose to her girlfriend at a Q&A session for his directorial debut Lost River at the South by Southwest festival on Saturday. 

The Hollywood Reporter says the fan said to Gosling: "I think your film was amazing, and I'm going to kind of take away from it for a bit if I can and ask my girlfriend of 11 years if she'll marry me." 

Gosling replied: "We've got a marriage proposal going on right now." 

When Gosling realised that people could not hear the proposal, he handed her the microphone.

With the answer a 'yes', Gosling said: "Well, let's go out on that note, shall we? "Congratulations to the happy couple."

You can watch the proposal below from 11' 38".