--- a/src/helper/yans-wifi-helper.cc	Thu Apr 15 21:31:26 2010 -0700
+++ b/src/helper/yans-wifi-helper.cc	Fri Apr 16 07:48:12 2010 +0200
@@ -409,7 +409,7 @@
       filename = pcapHelper.GetFilenameFromDevice (prefix, device);
     }
 
-  Ptr<PcapFileWrapper> file = pcapHelper.CreateFile (filename, "w", m_pcapDlt);
+  Ptr<PcapFileWrapper> file = pcapHelper.CreateFile (filename, std::ios::out, m_pcapDlt);
 
   phy->TraceConnectWithoutContext ("PromiscSnifferTx", MakeBoundCallback (&PcapSniffTxEvent, file));
   phy->TraceConnectWithoutContext ("PromiscSnifferRx", MakeBoundCallback (&PcapSniffRxEvent, file));