Ethan Hawke is thrilled by the success of 'The Purge'.

The low-budget horror film surprisingly topped the US box office upon its release last week, grossing more than $36 million on a modest $3 million budget, and the actor says it's a ''lot of fun'' to see the movie succeed against blockbusters such as 'Fast & Furious 6' and 'After Earth'.

He told Entertainment Weekly: ''To see it work, when you're up against all these movies that they spent $100 million making, it's a lot of fun. I mean, I slept on the producers' couch the whole time we shot the movie, and we were just the biggest movie of the weekend. It feels a little bit like some Robin Hood s**t.''

The modest actor admits he doesn't measure the success of his movies by box office receipts and was prepared for the film to flop as long as he enjoyed it.

He explained: ''I decided months ago that I loved 'The Purge' and I felt it was a cool movie. I would love it even if it bombed. I've had so few movies ever make money in my 20-year career. I've learned not to care about it.''

'The Purge' sees Hawke star as a family man who must protect his wife and children from home invaders on a frightful night where all crime, including murder is made legal.