lib/PublicInbox/SharedKV.pm | 7 ++++++-
 t/shared_kv.t               | 1 +

diff --git a/lib/PublicInbox/SharedKV.pm b/lib/PublicInbox/SharedKV.pm
index 52a7424eb19fe8a733c153b2ca94988942f84165..983952f59a961a08867aa25bed5f55543d00ba01 100644
--- a/lib/PublicInbox/SharedKV.pm
+++ b/lib/PublicInbox/SharedKV.pm
@@ -36,7 +36,6 @@ 	v VARBINARY NOT NULL,
 	UNIQUE (k)
 )
 
-		$dbh->do('CREATE INDEX IF NOT EXISTS idx_v ON kv (v)');
 		$dbh;
 	}
 }
@@ -57,6 +56,12 @@ 		open my $fh, '+>>', $f or die "failed to open $f: $!";
 		PublicInbox::Spawn::nodatacow_fd(fileno($fh));
 	}
 	$self;
+}
+
+sub index_values {
+	my ($self) = @_;
+	my $lock = $self->lock_for_scope;
+	$self->dbh($lock)->do('CREATE INDEX IF NOT EXISTS idx_v ON kv (v)');
 }
 
 sub set_maybe {
diff --git a/t/shared_kv.t b/t/shared_kv.t
index 4b72746238407c493075b94a6e899fd41aa14b0f..ad901328360bfa3e755cd7d2d951eb2dfbbd700c 100644
--- a/t/shared_kv.t
+++ b/t/shared_kv.t
@@ -26,6 +26,7 @@ is($skv->get($dead), $cafe, 'get after xchg');
 is($skv->xchg($dead, undef), $cafe, 'xchg to undef');
 is($skv->get($dead), undef, 'get after xchg to undef');
 is($skv->get($cafe), $dead, 'get after set_maybe');
+ok($skv->index_values, 'index_values works');
 is($skv->replace_values($dead, $cafe), 1, 'replaced one by value');
 is($skv->get($cafe), $cafe, 'value updated');
 is($skv->replace_values($dead, $cafe), 0, 'replaced none by value');