--- a/src/internet/model/ipv4.h	Thu Jan 02 18:34:30 2014 +0100
+++ a/src/internet/model/ipv4.h	Fri Jan 10 15:08:04 2014 -0800
@@ -24,7 +24,6 @@ 
 #include "ns3/object.h"
 #include "ns3/socket.h"
 #include "ns3/callback.h"
-#include "ns3/ip-l4-protocol.h"
 #include "ns3/ipv4-address.h"
 #include "ipv4-route.h"
 #include "ipv4-interface-address.h"
@@ -35,6 +34,8 @@ 
 class NetDevice;
 class Packet;
 class Ipv4RoutingProtocol;
+class IpL4Protocol;
+class Ipv4Header;
 
 /**
  * \ingroup internet
--- a/src/internet/model/udp-socket-impl.h	Thu Jan 02 18:34:30 2014 +0100
+++ a/src/internet/model/udp-socket-impl.h	Fri Jan 10 15:08:04 2014 -0800
@@ -38,6 +38,8 @@ 
 class Node;
 class Packet;
 class UdpL4Protocol;
+class Ipv6Header;
+class Ipv6Interface;
 
 /**
  * \ingroup udp