diff --git a/unix/xserver/hw/vnc/xvnc.cc b/unix/xserver/hw/vnc/xvnc.cc

index 5c0e171..c79ad18 100644

--- a/unix/xserver/hw/vnc/xvnc.cc

+++ b/unix/xserver/hw/vnc/xvnc.cc

@@ -352,7 +352,10 @@ static

 bool displayNumFree(int num)

 {

     try {

-	network::TcpListener l(NULL, 6000+num);

+      // Attempt to create TCPListeners on that port.

+      // They go out of scope immediately and are destroyed.

+      std::list<network::TcpListener> dummy;

+      network::createTcpListeners (&dummy, 0, 6000+num);

     } catch (rdr::Exception& e) {

 	return false;

     }