lib/PublicInbox/View.pm | 8 ++++++++

diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 2cf7e4f01ff120c8c6b4ef3634b944c7f0332043..5f9ecd108aacf444b1ad07a46bfd2b356865ecf8 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -729,8 +729,16 @@ sub thread_results {
 	my ($msgs, $nosubject) = @_;
 	require PublicInbox::Thread;
 	my $th = PublicInbox::Thread->new(@$msgs);
+
+	# WARNING! both these Mail::Thread knobs were found by inspecting
+	# the Mail::Thread 2.55 source code, and we have some monkey patches
+	# in PublicInbox::Thread to fix memory leaks.  Since Mail::Thread
+	# appears unmaintained, I suppose it's safe to depend on these
+	# variables for now:
 	no warnings 'once';
 	$Mail::Thread::nosubject = $nosubject;
+	# Keep ghosts with only a single direct child:
+	$Mail::Thread::noprune = 1;
 	$th->thread;
 	$th->order(*sort_ts);
 	$th