Which encoding do you use?
You can define the encoding of your sourcefile in the header. Or better: If you use characters beyond ASCII, you must define it.
Alex already mentioned
#encoding: utf-8
If you don't use UTF-8, but your local french codepage, you may use this header in the first line of your source code:
#encoding: cp1252
Perhaps you will get other encoding errors, when you read and save file. Details can be found in http://blog.grayproductions.net/articles/ruby_19s_three_default_encodings
