--- a/src/devices/wifi/dca-txop.cc	Thu Nov 08 13:57:50 2007 +0100
+++ b/src/devices/wifi/dca-txop.cc	Thu Nov 08 13:58:26 2007 +0100
@@ -155,6 +155,12 @@
   delete m_phyListener;
   delete m_queue;
   delete m_dcf;
+  m_accessListener = 0;
+  m_transmissionListener = 0;
+  m_navListener = 0;
+  m_phyListener = 0;
+  m_queue = 0;
+  m_dcf = 0;
 }
 
 void