diff --git a/examples/wireless/wifi-hidden-terminal.cc b/examples/wireless/wifi-hidden-terminal.cc
index 88e306325..1aef9e9a1 100644
--- a/examples/wireless/wifi-hidden-terminal.cc
+++ b/examples/wireless/wifi-hidden-terminal.cc
@@ -58,8 +58,8 @@ void experiment (bool enableCtsRts)
   // 3. Create propagation loss matrix
   Ptr<MatrixPropagationLossModel> lossModel = CreateObject<MatrixPropagationLossModel> ();
   lossModel->SetDefaultLoss (200); // set default loss to 200 dB (no link)
-  lossModel->SetLoss (nodes.Get (0), nodes.Get (1), 50); // set symmetric loss 0 <-> 1 to 50 dB
-  lossModel->SetLoss (nodes.Get (2), nodes.Get (1), 50); // set symmetric loss 2 <-> 1 to 50 dB
+  lossModel->SetLoss (nodes.Get (0)->GetObject<MobilityModel>(), nodes.Get (1)->GetObject<MobilityModel>(), 50); // set symmetric loss 0 <-> 1 to 50 dB
+  lossModel->SetLoss (nodes.Get (2)->GetObject<MobilityModel>(), nodes.Get (1)->GetObject<MobilityModel>(), 50); // set symmetric loss 2 <-> 1 to 50 dB
 
   // 4. Create & setup wifi channel
   Ptr<YansWifiChannel> wifiChannel = CreateObject <YansWifiChannel> ();
diff --git a/src/devices/wifi/wifi-test.cc b/src/devices/wifi/wifi-test.cc
index cb328fee8..c9309f81d 100644
--- a/src/devices/wifi/wifi-test.cc
+++ b/src/devices/wifi/wifi-test.cc
@@ -258,7 +258,7 @@ InterferenceHelperSequenceTest::DoRun (void)
   Ptr<Node> senderA = CreateOne (Vector (5.0, 0.0, 0.0), channel);
   Ptr<Node> senderB = CreateOne (Vector (-5.0, 0.0, 0.0), channel);
 
-  propLoss->SetLoss (senderB, rxOnly, 0, true);
+  propLoss->SetLoss (senderB->GetObject<MobilityModel>(), rxOnly->GetObject<MobilityModel>(), 0, true);
   propLoss->SetDefaultLoss (999);
 
   Simulator::Schedule (Seconds (1.0),
diff --git a/src/propagation/model/propagation-loss-model.cc b/src/propagation/model/propagation-loss-model.cc
index 7af86131f..26a5565e6 100644
--- a/src/propagation/model/propagation-loss-model.cc
+++ b/src/propagation/model/propagation-loss-model.cc
@@ -747,10 +747,8 @@ MatrixPropagationLossModel::SetDefaultLoss (double loss)
 }
 
 void
-MatrixPropagationLossModel::SetLoss (Ptr<Object> a, Ptr<Object> b, double loss, bool symmetric)
+MatrixPropagationLossModel::SetLoss (Ptr<MobilityModel> ma, Ptr<MobilityModel> mb, double loss, bool symmetric)
 {
-  Ptr<MobilityModel> ma = a->GetObject<MobilityModel> ();
-  Ptr<MobilityModel> mb = b->GetObject<MobilityModel> ();
   NS_ASSERT (ma != 0 && mb != 0);
 
   MobilityPair p = std::make_pair(ma, mb);
@@ -767,7 +765,7 @@ MatrixPropagationLossModel::SetLoss (Ptr<Object> a, Ptr<Object> b, double loss,
 
   if (symmetric)
     {
-      SetLoss (b, a, loss, false);
+      SetLoss (mb, ma, loss, false);
     }
 }
 
diff --git a/src/propagation/model/propagation-loss-model.h b/src/propagation/model/propagation-loss-model.h
index b23733233..1e3b317ba 100644
--- a/src/propagation/model/propagation-loss-model.h
+++ b/src/propagation/model/propagation-loss-model.h
@@ -497,12 +497,12 @@ public:
    * \brief Set loss (in dB, positive) between pair of ns-3 objects
    * (typically, nodes).
    * 
-   * \param a           Source object
-   * \param b           Destination object
+   * \param ma          Source mobility model
+   * \param mb          Destination mobility model
    * \param loss        a -> b path loss, positive in dB
    * \param symmetric   If true (default), both a->b and b->a paths will be affected
    */ 
-  void SetLoss (Ptr<Object> a, Ptr<Object> b, double loss, bool symmetric = true);
+  void SetLoss (Ptr<MobilityModel> a, Ptr<MobilityModel> b, double loss, bool symmetric = true);
   /// Set default loss (in dB, positive) to be used, infinity if not set
   void SetDefaultLoss (double);
   
diff --git a/src/propagation/test/propagation-loss-model-test-suite.cc b/src/propagation/test/propagation-loss-model-test-suite.cc
index 730884df7..373c6d609 100644
--- a/src/propagation/test/propagation-loss-model-test-suite.cc
+++ b/src/propagation/test/propagation-loss-model-test-suite.cc
@@ -368,23 +368,20 @@ MatrixPropagationLossModelTestCase::~MatrixPropagationLossModelTestCase ()
 void
 MatrixPropagationLossModelTestCase::DoRun (void)
 {
-  Ptr<Object> n[3];
   Ptr<MobilityModel> m[3];
   for (int i = 0; i < 3; ++i)
     {
-      n[i] = CreateObject<Object> ();
       m[i] = CreateObject<ConstantPositionMobilityModel> ();
-      n[i]->AggregateObject (m[i]);
     }
   
   MatrixPropagationLossModel loss;
   // no loss by default
   loss.SetDefaultLoss (0);       
   // -10 dB for 0 -> 1 and 1 -> 0
-  loss.SetLoss (n[0], n[1], 10); 
+  loss.SetLoss (m[0], m[1], 10);
   // -30 dB from 0 to 2 and -100 dB from 2 to 0
-  loss.SetLoss (n[0], n[2], 30, /*symmetric = */false); 
-  loss.SetLoss (n[2], n[0], 100, /*symmetric = */false); 
+  loss.SetLoss (m[0], m[2], 30, /*symmetric = */false);
+  loss.SetLoss (m[2], m[0], 100, /*symmetric = */false);
   // default from 1 to 2
   
   NS_TEST_ASSERT_MSG_EQ (loss.CalcRxPower (0, m[0], m[1]), -10, "Loss 0 -> 1 incorrect");