diff --git a/grpc_request_buffering.t b/grpc_request_buffering.t
index d8541a7..de7baef 100644
--- a/grpc_request_buffering.t
+++ b/grpc_request_buffering.t
@@ -88,14 +88,23 @@
 ($frame) = grep { $_->{type} eq "HEADERS" } @$frames;
 is($frame->{headers}{'x-body'}, 'Hello', 'request body in memory');
 
-# expect body cleanup is disabled with preserve_output (ticket #1565).
-# after request body first bytes were proxied on behalf of initial window size,
-# send response header from upstream, this leads to body cleanup code path
+# tcp_nopush usage on peer connections
+# reopen window for request body after initial window was exhausted
+
+TODO: {
+local $TODO = 'not yet' if $t->read_file('nginx.conf') =~ /sendfile on/
+	and !$t->has_version('1.15.1') and $^O eq 'freebsd';
 
 $frames = $f->{http_start}('/proxy');
 is(eval(join '+', map { $_->{length} } grep { $_->{type} eq "DATA" } @$frames),
 	65535, 'preserve_output - first body bytes');
 
+}
+
+# expect body cleanup is disabled with preserve_output (ticket #1565).
+# after request body first bytes were proxied on behalf of initial window size,
+# send response header from upstream, this leads to body cleanup code path
+
 TODO: {
 local $TODO = 'not yet' unless $t->has_version('1.15.1');