Playing a bit more, I found out that when encoding "dr�ber" as ISO-8859-15, i.e.: 64 72 c3 62 65 72 my Perl script (when run with LANG=de_DE.UTF-8) accepts '�' as letter. However when using an encoding as UTF-8, i.e.: 64 72 c3 bc 62 65 72 I get the result as described in comment #0 already.