Can't call NEXT::f from B::g

$ perl test.pl
Can't call NEXT::f from B::g at /home/porton/t/test2.pl line 10

Why the error?

#!/usr/bin/perl -w

use NEXT;

package A;
sub f { print "123\n" }

package B;
use base 'A';
sub g { shift->NEXT::f }

B->g;
.