Index: binary-improvements2/SpaceWizards.HttpListener/src/System/Net/Managed/HttpEndPointListener.cs
===================================================================
--- binary-improvements2/SpaceWizards.HttpListener/src/System/Net/Managed/HttpEndPointListener.cs	(revision 384)
+++ binary-improvements2/SpaceWizards.HttpListener/src/System/Net/Managed/HttpEndPointListener.cs	(revision 385)
@@ -67,4 +67,11 @@
             _endpoint = new IPEndPoint(addr, port);
             _socket = new Socket(addr.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
+
+            if (addr.AddressFamily == AddressFamily.InterNetworkV6) {
+                // Make sure that all platforms behave the same for IPv6 sockets (at least Linux by
+                // default has them in dual mode, so it would conflict with the explicit IPv4 socket)
+                _socket.DualMode = false;
+            }
+
             _socket.Bind(_endpoint);
             _socket.Listen(500);