Does the file contains the special character? Or does the file name contain it? Archive::Zip should treat all files as binary content and not care about the encoding of the file.

The file name is a different issue. My impression is that the ZIP format, Archive::Zip, and Unix file systems store file names as binary strings. They don't care about the encoding. However, the Perl could be translating the strings from native encoding to UTF-8. Also, some programs handling Unix file names assume they are UTF-8 (or a different native encoding). They will consider the German character as either invalid and translate it to something else.