Use a newer Perl, really. 5.6.1 is 6 years old, and in software years, that's very old :)

Also, use :encoding(UTF-8) when reading a file. If you use :utf8, perl assumes that everything is valid UTF8 data. When it happens to be invalid, for whatever reason, perl won't detect it. It will cause internal corruption, and that can theoretically lead to security problems and if you're lucky, crashes.

:utf8 is safe for *writing* only.