diff --git a/test/socket/test_socket.rb b/test/socket/test_socket.rb
index 590a7ab..0e7fef4 100644
--- a/test/socket/test_socket.rb
+++ b/test/socket/test_socket.rb
@@ -575,4 +575,30 @@ class TestSocket < Test::Unit::TestCase
       assert_instance_of(Socket::Ifaddr, ifaddr)
     }
   end
+
+  def test_tcp_fastopen
+    port = random_port
+    serv = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM)
+    serv.setsockopt(Socket::SOL_TCP, Socket::TCP_FASTOPEN, 5)
+    addrinfo = Addrinfo.new(Socket.sockaddr_in(port, "localhost"))
+    serv.bind(addrinfo)
+    serv.listen(1)
+    th = Thread.new do
+      sock, = serv.accept
+      begin
+        assert_equal("foo", sock.read)
+      ensure
+        sock.close if sock && !sock.closed?
+      end
+    end
+
+    sock = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM)
+    len = sock.send("foo", Socket::MSG_FASTOPEN, Socket.sockaddr_in(port, "localhost"))
+    assert_equal(len, 3)
+    sock.close
+    assert(th.join(10))
+  ensure
+    th.kill if th
+    sock.close if sock && !sock.closed?
+  end if defined?(Socket::TCP_FASTOPEN) && defined?(Socket::MSG_FASTOPEN)
 end if defined?(Socket)