lib/PublicInbox/HTTPD/Async.pm | 3 +++

diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index 63985026e2912fbe9927cc68298fca47c7c6c394..bedb397d0f9cdbf7b143615613fb117510549ea4 100644
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -32,4 +32,7 @@ 	$self->{cb} = undef;
 	$self->SUPER::close(@_);
 }
 
+# do not let ourselves be closed during graceful termination
+sub busy () { $_[0]->{cb} }
+
 1;