-push @out, $self->msg('wwv1', 'k') unless $args{k} && $args{k} >= 0 && $args{k} <= 9;
-push @out, $self->msg('wwv1', 'a') unless $args{a} && $args{a} >= 0 && $args{a} <= 400;
-push @out, $self->msg('wwv1', 'sf') unless $args{sf} && $args{sf} >= 65 && $args{sf} <= 300;
+push @out, $self->msg('wwv1', 'k') unless defined $args{k} && $args{k} >= 0 && $args{k} <= 9;
+push @out, $self->msg('wwv1', 'a') unless defined $args{a} && $args{a} >= 0 && $args{a} <= 400;
+push @out, $self->msg('wwv1', 'sf') unless defined $args{sf} && $args{sf} >= 65 && $args{sf} <= 300;