use warnings;
use strict 'subs';

my %hash = qw (k1 v1 k2 v2 k3 v3);

$hash{k1} = 42;                  # is fine
@hash{k1,k2,k3} = (1,2,3);       # BANG! Bareword "k1" not allowed...
@hash{qw(k1 k2 k3)} = (1,2,3);   # is fine