lib/PublicInbox/HTTP.pm        | 18 ++++++++++++++++++
 lib/PublicInbox/HTTPD/Async.pm |  2 ++

diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index f69056f87932980cb8dffe2d41ae9d1c3be4297b..d523bd42a3bd6571ec33d6074779a8dea7fe56ab 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -219,6 +219,24 @@ 	if (defined(my $body = $res->[2])) {
 		if (ref $body eq 'ARRAY') {
 			$write->($_) foreach @$body;
 			$close->();
+		} elsif ($body->can('async_pass')) { # HTTPD::Async
+			# prevent us from reading the body faster than we
+			# can write to the client
+			my $restart_read = sub { $body->watch_read(1) };
+			$body->async_pass(sub {
+				local $/ = \8192;
+				my $buf = $body->getline;
+				if (defined $buf) {
+					$write->($buf);
+					if ($self->{write_buf}) {
+						$body->watch_read(0);
+						$self->write($restart_read);
+					}
+					return; # continue waiting
+				}
+				$body->close;
+				$close->();
+			});
 		} else {
 			my $pull;
 			$pull = sub {
diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index bedb397d0f9cdbf7b143615613fb117510549ea4..ceba738e3ce3f9793c314b16c7a3fe3733b55358 100644
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -21,10 +21,12 @@ 	$self->watch_read(1);
 	$self;
 }
 
+sub async_pass { $_[0]->{cb} = $_[1] }
 sub event_read { $_[0]->{cb}->() }
 sub event_hup { $_[0]->{cb}->() }
 sub event_err { $_[0]->{cb}->() }
 sub sysread { shift->{sock}->sysread(@_) }
+sub getline { $_[0]->{sock}->getline };
 
 sub close {
 	my $self = shift;