script/public-inbox-index | 2 +-

diff --git a/script/public-inbox-index b/script/public-inbox-index
index db7ebbab6421ec2cc1b849e4259b2ac82d6d745b..2a7a524b34abee1765c3adc9288b64cf29dac78e 100755
--- a/script/public-inbox-index
+++ b/script/public-inbox-index
@@ -101,7 +101,7 @@ 	if (ref($repo) && ($repo->{version} || 1) == 2) {
 		eval { require PublicInbox::V2Writable };
 		die "v2 requirements not met: $@\n" if $@;
 		my $v2w = eval {
-			local $ENV{NPROC} = $jobs if $jobs;
+			$jobs and local $ENV{NPROC} = $jobs;
 			PublicInbox::V2Writable->new($repo);
 		};
 		if (defined $jobs) {