--- a/src/internet/model/ipv4-l3-protocol.cc	Mon Dec 02 23:05:14 2013 +0100
+++ b/src/internet/model/ipv4-l3-protocol.cc	Wed Dec 04 20:56:33 2013 +0100
@@ -891,6 +891,7 @@
         }
       NS_LOG_LOGIC ("Got last fragment, Packet is complete " << *p );
       ipHeader.SetFragmentOffset (0);
+      ipHeader.SetPayloadSize (p->GetSize () + ipHeader.GetSerializedSize ());
     }
 
   m_localDeliverTrace (ipHeader, p, iif);