-chomp(my $git_dir = `git rev-parse --git-dir 2>/dev/null`);
-plan skip_all => "$0 must be run from a git working tree" if $?;
+my $git_dir = xqx([qw(git rev-parse --git-dir)], undef, {2 => \(my $null)});
+$? == 0 or plan skip_all => "$0 must be run from a git working tree";
+chomp $git_dir;