diff --git a/src/spectrum/examples/adhoc-aloha-ideal-phy-matrix-propagation-loss-model.cc b/src/spectrum/examples/adhoc-aloha-ideal-phy-matrix-propagation-loss-model.cc
index b9e8fb345..b8722d33b 100644
--- a/src/spectrum/examples/adhoc-aloha-ideal-phy-matrix-propagation-loss-model.cc
+++ b/src/spectrum/examples/adhoc-aloha-ideal-phy-matrix-propagation-loss-model.cc
@@ -80,7 +80,7 @@ public:
    * \param rxPhy the receiving PHY
    * \param lossDb the loss in dB
    */
-  void UpdatePathloss (std::string context, Ptr<SpectrumPhy> txPhy, Ptr<SpectrumPhy> rxPhy, double lossDb);
+  void UpdatePathloss (std::string context, Ptr<const SpectrumPhy> txPhy, Ptr<const SpectrumPhy> rxPhy, double lossDb);
 
   /** 
    * print the stored pathloss values to standard output
@@ -94,10 +94,12 @@ private:
 
 void
 GlobalPathlossDatabase::UpdatePathloss (std::string context, 
-                                        Ptr<SpectrumPhy> txPhy, 
-                                        Ptr<SpectrumPhy> rxPhy, 
+                                        Ptr<const SpectrumPhy> txPhyConst, 
+                                        Ptr<const SpectrumPhy> rxPhyConst, 
                                         double lossDb)
 {
+  Ptr<SpectrumPhy> txPhy = ConstCast<SpectrumPhy> (txPhyConst);
+  Ptr<SpectrumPhy> rxPhy = ConstCast<SpectrumPhy> (rxPhyConst);
   uint32_t txNodeId = txPhy->GetMobility ()->GetObject<Node> ()->GetId ();
   uint32_t rxNodeId = rxPhy->GetMobility ()->GetObject<Node> ()->GetId ();
   m_pathlossMap[txNodeId][rxNodeId] = lossDb;
@@ -195,7 +197,7 @@ int main (int argc, char** argv)
   Config::Connect ("/NodeList/*/DeviceList/*/Phy/RxEndOk", MakeCallback (&PhyRxEndOkTrace));
 
   GlobalPathlossDatabase globalPathlossDatabase;
-  Config::Connect ("/ChannelList/*/PropagationLoss",
+  Config::Connect ("/ChannelList/*/$ns3::SpectrumChannel/PathLoss", 
                    MakeCallback (&GlobalPathlossDatabase::UpdatePathloss, &globalPathlossDatabase));
 
   g_rxBytes = 0;