lib/PublicInbox/SearchIdx.pm | 4 ++++

diff --git a/lib/PublicInbox/SearchIdx.pm b/lib/PublicInbox/SearchIdx.pm
index 7ac16ec283bf6c059c2f7ac14a12706da5f6f319..446cfb0d50afd8be723a24c4f6f5751de80ba548 100644
--- a/lib/PublicInbox/SearchIdx.pm
+++ b/lib/PublicInbox/SearchIdx.pm
@@ -561,6 +561,10 @@ 			++$vivified;
 			1;
 		});
 	}
+	if ($vivified > 1) {
+		my $id = '<'.join('> <', @$mids).'>';
+		warn "BUG: vivified multiple ($vivified) ghosts for $id\n";
+	}
 	# not really important, but we return any vivified ghost docid, here:
 	return $doc_id if defined $doc_id;
 	link_doc($self, $doc, $refs, $old_tid);