new file mode 100644
--- /dev/null
+++ b/proxy_chunked_extra.t
@@ -0,0 +1,120 @@
+#!/usr/bin/perl
+
+# (C) Maxim Dounin
+# (C) Nginx, Inc.
+
+# Test for http backend returning response with Transfer-Encoding: chunked,
+# followed by some extra data.
+
+###############################################################################
+
+use warnings;
+use strict;
+
+use Test::More;
+use Socket qw/ CRLF /;
+
+BEGIN { use FindBin; chdir($FindBin::Bin); }
+
+use lib 'lib';
+use Test::Nginx;
+
+###############################################################################
+
+select STDERR; $| = 1;
+select STDOUT; $| = 1;
+
+my $t = Test::Nginx->new()->has(qw/http proxy/)->plan(1);
+
+$t->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon off;
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        proxy_buffer_size 128;
+        proxy_buffers 4 128;
+
+        location / {
+            proxy_pass http://127.0.0.1:8081;
+            proxy_read_timeout 1s;
+        }
+    }
+}
+
+EOF
+
+$t->run_daemon(\&http_chunked_daemon);
+$t->run()->waitforsocket('127.0.0.1:' . port(8081));
+
+###############################################################################
+
+TODO: {
+local $TODO = 'not yet' unless $t->has_version('1.19.1');
+
+like(http_get('/'), qr/200 OK(?!.*zzz)/s, 'chunked with extra data');
+
+}
+
+###############################################################################
+
+sub http_chunked_daemon {
+	my $server = IO::Socket::INET->new(
+		Proto => 'tcp',
+		LocalAddr => '127.0.0.1:' . port(8081),
+		Listen => 5,
+		Reuse => 1
+	)
+		or die "Can't create listening socket: $!\n";
+
+	local $SIG{PIPE} = 'IGNORE';
+
+	while (my $client = $server->accept()) {
+		$client->autoflush(1);
+
+		while (<$client>) {
+			last if (/^\x0d?\x0a?$/);
+		}
+
+		# return a large response start to allocate
+		# multiple buffers; stop at the buffer end
+
+		print $client ""
+			. "HTTP/1.1 200 OK" . CRLF
+			. "Connection: close" . CRLF
+			. "Transfer-Encoding: chunked" . CRLF . CRLF
+			. "80" . CRLF . ("x" x 126) . CRLF . CRLF
+			. "80" . CRLF . ("x" x 126) . CRLF . CRLF
+			. "80" . CRLF . ("x" x 126) . CRLF . CRLF
+			. "80" . CRLF . ("x" x 126) . CRLF . CRLF
+			. "20" . CRLF . ("x" x 30) . CRLF . CRLF;
+
+		select(undef, undef, undef, 0.3);
+
+		# fill three full buffers here, so they are
+		# processed in order, regardless of the
+		# p->upstream_done flag set
+
+		print $client ""
+			. "75" . CRLF . ("y" x 115) . CRLF . CRLF
+			. "0" . CRLF . CRLF
+			. "75" . CRLF . ("z" x 115) . CRLF . CRLF
+			. "0" . CRLF . CRLF
+			. "75" . CRLF . ("z" x 115) . CRLF . CRLF
+			. "0" . CRLF . CRLF;
+
+		close $client;
+	}
+}
+
+###############################################################################