lib/PublicInbox/MID.pm | 4 +---

diff --git a/lib/PublicInbox/MID.pm b/lib/PublicInbox/MID.pm
index d7a42c38573b17111458ddccd32e821355f79b91..33d5af7450a2610702591c7ad864cb81e981084c 100644
--- a/lib/PublicInbox/MID.pm
+++ b/lib/PublicInbox/MID.pm
@@ -120,9 +120,7 @@ 		if (length($mid) > MAX_MID_SIZE) {
 			warn "Message-ID: <$mid> too long, truncating\n";
 			$mid = substr($mid, 0, MAX_MID_SIZE);
 		}
-		next if $seen->{$mid};
-		push @ret, $mid;
-		$seen->{$mid} = 1;
+		push(@ret, $mid) unless $seen->{$mid}++;
 	}
 	\@ret;
 }