lib/PublicInbox/SearchIdxPart.pm | 2 ++

diff --git a/lib/PublicInbox/SearchIdxPart.pm b/lib/PublicInbox/SearchIdxPart.pm
index 64e5263657160430ecec3de2fa88d06adec3f155..63fc70491354ea5aa1933c7a2325637fca3a9e59 100644
--- a/lib/PublicInbox/SearchIdxPart.pm
+++ b/lib/PublicInbox/SearchIdxPart.pm
@@ -11,6 +11,8 @@ 	my $self = $class->SUPER::new($v2writable->{-inbox}, 1, $part);
 	$self->{threader} = $threader;
 	my ($r, $w);
 	pipe($r, $w) or die "pipe failed: $!\n";
+	binmode $r, ':raw';
+	binmode $w, ':raw';
 	my $pid = fork;
 	defined $pid or die "fork failed: $!\n";
 	if ($pid == 0) {