Bruce Willis is concerned he may be replaced in the 'Die Hard' franchise.

The 55-year-old actor - who is currently filming his fifth film playing action hero John McClane - admitted that while he thinks his job is safe at the moment, he will be hanging up his character's white vest after 'Die Hard 6' to avoid being replaced.

He said: "In the next few years they could easily find a replacement for me or call the character someone else. But for me, I want to do 'Die Hard 5', then one final 'Die Hard' movie - 'Die Hard 6' - before finally hanging that white vest up for good.

"At the moment, I can run and I can fight on screen. But there will come a time when I no longer want to do that. That's when I'll step away from the 'Die Hard' films."

The actor also revealed he came up with his one of his character's key line after he had a disagreement with the film's producers.

He explained to FHM magazine: "Take the first 'Die Hard', I was the one who came up with the line, 'Yippee ki-yay motherf****r!' The Producers were trying to give me their take on how I should say a certain line at that point in the movie, and I disagreed.

"So they said, 'You do it'. So I did. Yippee ki-yay was some goofy thing that cowboys used to say in those movies, so I added the 'motherf****r' bit as I thought it was a nice, contrasting combination of the two images. And it worked. That expression's really stuck around, that's for sure."