PLPERL function error - utf-8 to iso8859-1

Trying to create a plperl function to strip non-friendly mainframe
characters from a string.  However, when I try to add the Trademark symbol
(™) as a replace criteria, PG spits back an error:
ERROR:  Could not convert UTF-8 to ISO8859-1
Any way I get around this?

CREATE OR REPLACE FUNCTION public.mainframe_description(varchar)
  RETURNS varchar AS
'
     my($desc) = @_;
        $desc =~ s/®//g;
        $desc =~ s//e/g;
     $desc =~ s/ô/o/g;
     $desc =~ s/æ/E/g;
     $desc =~ s/Ò/ /g;
     $desc =~ s/Ó/ /g;
     $desc =~ s/è/e/g;
     $desc =~ s/Ô//g;
     $desc =~ s/É/E/g;
     $desc =~ s/°//g;
     $desc =~ s/é/e/g;
     $desc =~ s/~Y//g;
     $desc =~ s/Ö//g;
     /*Error happens here */
     $desc =~ s/™//g;
     return $desc;
'
  LANGUAGE 'plperl' VOLATILE;
COMMENT ON FUNCTION public.mainframe_description(varchar) IS 'Return a
clean description for mainframe input';


TIA

Patrick Hatcher