use locale;
utf8::upgrade( my $s = chr(0xC9) );   # e-acute
print "Outside char class: ", $s =~ m/\w/   ? "" : "no ", "match\n";
print "Inside char class:  ", $s =~ m/[\w]/ ? "" : "no ", "match\n";

##</code><code>##

LANG=en_CA.utf8 perl test.pl
Outside char class: no match
Inside char class:  match