lib/PublicInbox/HTTPD/Async.pm | 3 ++-
 t/spawn.t                      | 5 +++++

diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index bd1fd8faf2c1ea49569a702a16c75407ffd4220e..1de9501d18c43528e4ce634458b394d089d6eb41 100644
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -37,7 +37,8 @@ 		cb => $cb, # initial read callback
 		arg => $arg, # arg for $cb
 		end_obj => $end_obj, # like END{}, can ->event_step
 	}, $class;
-	IO::Handle::blocking($io, 0);
+	my $pp = tied *$io;
+	$pp->{fh}->blocking(0) // die "$io->blocking(0): $!";
 	$self->SUPER::new($io, EPOLLIN | EPOLLET);
 }
 
diff --git a/t/spawn.t b/t/spawn.t
index 0eed79bbbb5802343717a4590ab2e79406c9ccd6..6f811ec163df75fab559a2c119b723daad23f27f 100644
--- a/t/spawn.t
+++ b/t/spawn.t
@@ -77,6 +77,11 @@
 {
 	my $fh = popen_rd([qw(printf foo\nbar)]);
 	ok(fileno($fh) >= 0, 'tied fileno works');
+	my $tfh = (tied *$fh)->{fh};
+	is($tfh->blocking(0), 1, '->blocking was true');
+	is($tfh->blocking, 0, '->blocking is false');
+	is($tfh->blocking(1), 0, '->blocking was true');
+	is($tfh->blocking, 1, '->blocking is true');
 	my @line = <$fh>;
 	is_deeply(\@line, [ "foo\n", 'bar' ], 'wantarray works on readline');
 }