Veber agreed saying Wilder "made the same mistake I made when I wrote the story as a play in Paris. It was not a great success because I did not make the killer tough enough. I changed that when I wrote the film. Lino Ventura played the part as a really hard killer. Billy Wilder cast Matthau in the part and that was a mistake. You cannot be frightened by him. He would have been better off with someone like Charles Bronson."