use Encode qw(_utf8_on); $a = [['']]; foreach (@$a) { _utf8_on($_) foreach @$_ } # my way print utf8::is_utf8( $a->[0][0] ),$/; $a = [['']]; _utf8_on( $_ ) for map @$_, @{$a}; # Aristotle's way print utf8::is_utf8( $a->[0][0] ),$/; __END__ 1