diff --git a/CHANGES.html b/CHANGES.html
index 247481113..9ce02915b 100644
--- a/CHANGES.html
+++ b/CHANGES.html
@@ -86,6 +86,13 @@ width standards has had a change in capitalization:
 <li> WIFI_PHY_STANDARD_80211_10Mhz was changed to WIFI_PHY_STANDARD_80211_10MHZ
 <li> WIFI_PHY_STANDARD_80211_5Mhz was changed to WIFI_PHY_STANDARD_80211_5MHZ
 </ul>
+<li> In the SpectrumPhy base class, the methods to get/set the
+  MobilityModel and the NetDevice were previously working with
+  opaque Ptr&#60;Object&#62;. Now all these methods have been
+  changed so that they work with Ptr&#60;NetDevice&#62;
+  and Ptr&#60;MobilityModel&#62; as appropriate. See <A href="https://www.nsnam.org/bugzilla/show_bug.cgi?id=1271">Bug 1271</A> on
+  bugzilla for the motivation.
+</li>
 </ul>
 
 <h2>Changed behavior:</h2>
diff --git a/src/lte/model/lte-spectrum-phy.cc b/src/lte/model/lte-spectrum-phy.cc
index 4534666c0..41303e0f9 100644
--- a/src/lte/model/lte-spectrum-phy.cc
+++ b/src/lte/model/lte-spectrum-phy.cc
@@ -104,7 +104,7 @@ LteSpectrumPhy::GetTypeId (void)
 
 
 
-Ptr<Object>
+Ptr<NetDevice>
 LteSpectrumPhy::GetDevice ()
 {
   NS_LOG_FUNCTION (this);
@@ -112,7 +112,7 @@ LteSpectrumPhy::GetDevice ()
 }
 
 
-Ptr<Object>
+Ptr<MobilityModel>
 LteSpectrumPhy::GetMobility ()
 {
   NS_LOG_FUNCTION (this);
@@ -121,7 +121,7 @@ LteSpectrumPhy::GetMobility ()
 
 
 void
-LteSpectrumPhy::SetDevice (Ptr<Object> d)
+LteSpectrumPhy::SetDevice (Ptr<NetDevice> d)
 {
   NS_LOG_FUNCTION (this << d);
   m_device = d;
@@ -129,7 +129,7 @@ LteSpectrumPhy::SetDevice (Ptr<Object> d)
 
 
 void
-LteSpectrumPhy::SetMobility (Ptr<Object> m)
+LteSpectrumPhy::SetMobility (Ptr<MobilityModel> m)
 {
   NS_LOG_FUNCTION (this << m);
   m_mobility = m;
diff --git a/src/lte/model/lte-spectrum-phy.h b/src/lte/model/lte-spectrum-phy.h
index dde4f6254..468e5bc16 100644
--- a/src/lte/model/lte-spectrum-phy.h
+++ b/src/lte/model/lte-spectrum-phy.h
@@ -65,10 +65,10 @@ public:
 
   // inherited from SpectrumPhy
   void SetChannel (Ptr<SpectrumChannel> c);
-  void SetMobility (Ptr<Object> m);
-  void SetDevice (Ptr<Object> d);
-  Ptr<Object> GetMobility ();
-  Ptr<Object> GetDevice ();
+  void SetMobility (Ptr<MobilityModel> m);
+  void SetDevice (Ptr<NetDevice> d);
+  Ptr<MobilityModel> GetMobility ();
+  Ptr<NetDevice> GetDevice ();
   Ptr<const SpectrumModel> GetRxSpectrumModel () const;
 
   /**
@@ -182,9 +182,9 @@ private:
 
   EventId m_endRxEventId;
 
-  Ptr<Object> m_mobility;
+  Ptr<MobilityModel> m_mobility;
 
-  Ptr<Object> m_device;
+  Ptr<NetDevice> m_device;
 
   Ptr<SpectrumChannel> m_channel;
 
diff --git a/src/spectrum/helper/adhoc-aloha-noack-ideal-phy-helper.cc b/src/spectrum/helper/adhoc-aloha-noack-ideal-phy-helper.cc
index 2c2602b43..8ceeb2966 100644
--- a/src/spectrum/helper/adhoc-aloha-noack-ideal-phy-helper.cc
+++ b/src/spectrum/helper/adhoc-aloha-noack-ideal-phy-helper.cc
@@ -113,7 +113,7 @@ AdhocAlohaNoackIdealPhyHelper::Install (NodeContainer c) const
       dev->SetPhy (phy);
 
       NS_ASSERT (node);
-      phy->SetMobility (node);
+      phy->SetMobility (node->GetObject<MobilityModel> ());
 
       NS_ASSERT (dev);
       phy->SetDevice (dev);
diff --git a/src/spectrum/helper/spectrum-analyzer-helper.cc b/src/spectrum/helper/spectrum-analyzer-helper.cc
index fc1f9db34..221bbd8b2 100644
--- a/src/spectrum/helper/spectrum-analyzer-helper.cc
+++ b/src/spectrum/helper/spectrum-analyzer-helper.cc
@@ -142,7 +142,7 @@ SpectrumAnalyzerHelper::Install (NodeContainer c) const
       dev->SetPhy (phy);
 
       NS_ASSERT (node);
-      phy->SetMobility (node);
+      phy->SetMobility (node->GetObject<MobilityModel> ());
 
       NS_ASSERT (dev);
       phy->SetDevice (dev);
diff --git a/src/spectrum/helper/spectrum-helper.cc b/src/spectrum/helper/spectrum-helper.cc
index 53f9fff67..0aaf25120 100644
--- a/src/spectrum/helper/spectrum-helper.cc
+++ b/src/spectrum/helper/spectrum-helper.cc
@@ -215,7 +215,7 @@ SpectrumPhyHelper::Create (Ptr<Node> node, Ptr<NetDevice> device) const
   NS_ASSERT (m_channel);
   Ptr<SpectrumPhy> phy = (m_phy.Create ())->GetObject<SpectrumPhy> ();
   phy->SetChannel (m_channel);
-  phy->SetMobility (node);
+  phy->SetMobility (node->GetObject<MobilityModel> ());
   phy->SetDevice (device);
   return phy;
 }
diff --git a/src/spectrum/helper/waveform-generator-helper.cc b/src/spectrum/helper/waveform-generator-helper.cc
index 278e2fdfa..f08e39357 100644
--- a/src/spectrum/helper/waveform-generator-helper.cc
+++ b/src/spectrum/helper/waveform-generator-helper.cc
@@ -98,7 +98,7 @@ WaveformGeneratorHelper::Install (NodeContainer c) const
       dev->SetPhy (phy);
 
       NS_ASSERT (node);
-      phy->SetMobility (node);
+      phy->SetMobility (node->GetObject<MobilityModel> ());
 
       NS_ASSERT (dev);
       phy->SetDevice (dev);
diff --git a/src/spectrum/model/half-duplex-ideal-phy.cc b/src/spectrum/model/half-duplex-ideal-phy.cc
index a565c8c65..38b1aaaa8 100644
--- a/src/spectrum/model/half-duplex-ideal-phy.cc
+++ b/src/spectrum/model/half-duplex-ideal-phy.cc
@@ -126,7 +126,7 @@ HalfDuplexIdealPhy::GetTypeId (void)
 
 
 
-Ptr<Object>
+Ptr<NetDevice>
 HalfDuplexIdealPhy::GetDevice ()
 {
   NS_LOG_FUNCTION (this);
@@ -134,7 +134,7 @@ HalfDuplexIdealPhy::GetDevice ()
 }
 
 
-Ptr<Object>
+Ptr<MobilityModel>
 HalfDuplexIdealPhy::GetMobility ()
 {
   NS_LOG_FUNCTION (this);
@@ -143,7 +143,7 @@ HalfDuplexIdealPhy::GetMobility ()
 
 
 void
-HalfDuplexIdealPhy::SetDevice (Ptr<Object> d)
+HalfDuplexIdealPhy::SetDevice (Ptr<NetDevice> d)
 {
   NS_LOG_FUNCTION (this << d);
   m_netDevice = d;
@@ -151,7 +151,7 @@ HalfDuplexIdealPhy::SetDevice (Ptr<Object> d)
 
 
 void
-HalfDuplexIdealPhy::SetMobility (Ptr<Object> m)
+HalfDuplexIdealPhy::SetMobility (Ptr<MobilityModel> m)
 {
   NS_LOG_FUNCTION (this << m);
   m_mobility = m;
diff --git a/src/spectrum/model/half-duplex-ideal-phy.h b/src/spectrum/model/half-duplex-ideal-phy.h
index c7ad14f8a..3f54e9772 100644
--- a/src/spectrum/model/half-duplex-ideal-phy.h
+++ b/src/spectrum/model/half-duplex-ideal-phy.h
@@ -94,10 +94,10 @@ public:
 
   // inherited from SpectrumPhy
   void SetChannel (Ptr<SpectrumChannel> c);
-  void SetMobility (Ptr<Object> m);
-  void SetDevice (Ptr<Object> d);
-  Ptr<Object> GetMobility ();
-  Ptr<Object> GetDevice ();
+  void SetMobility (Ptr<MobilityModel> m);
+  void SetDevice (Ptr<NetDevice> d);
+  Ptr<MobilityModel> GetMobility ();
+  Ptr<NetDevice> GetDevice ();
   Ptr<const SpectrumModel> GetRxSpectrumModel () const;
   void StartRx (Ptr<PacketBurst> p, Ptr <const SpectrumValue> rxPsd, SpectrumType st, Time duration);
 
@@ -195,8 +195,8 @@ private:
 
   EventId m_endRxEventId;
 
-  Ptr<Object> m_mobility;
-  Ptr<Object> m_netDevice;
+  Ptr<MobilityModel> m_mobility;
+  Ptr<NetDevice> m_netDevice;
   Ptr<SpectrumChannel> m_channel;
 
   Ptr<SpectrumValue> m_txPsd;
diff --git a/src/spectrum/model/multi-model-spectrum-channel.cc b/src/spectrum/model/multi-model-spectrum-channel.cc
index acba76ca0..c3b84f9b0 100644
--- a/src/spectrum/model/multi-model-spectrum-channel.cc
+++ b/src/spectrum/model/multi-model-spectrum-channel.cc
@@ -222,7 +222,7 @@ MultiModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> orig
   NS_ASSERT (originalTxPowerSpectrum);
 
 
-  Ptr<MobilityModel> txMobility = txPhy->GetMobility ()->GetObject<MobilityModel> ();
+  Ptr<MobilityModel> txMobility = txPhy->GetMobility ();
   SpectrumModelUid_t txSpectrumModelUid = originalTxPowerSpectrum->GetSpectrumModelUid ();
   NS_LOG_LOGIC (" txSpectrumModelUid " << txSpectrumModelUid);
 
@@ -268,7 +268,7 @@ MultiModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> orig
               Ptr <SpectrumValue> rxPowerSpectrum = convertedTxPowerSpectrum->Copy ();
               Time delay = MicroSeconds (0); 
 
-              Ptr<MobilityModel> receiverMobility = (*rxPhyIterator)->GetMobility ()->GetObject<MobilityModel> ();
+              Ptr<MobilityModel> receiverMobility = (*rxPhyIterator)->GetMobility ();
 
               if (txMobility && receiverMobility)
                 {
@@ -296,11 +296,11 @@ MultiModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> orig
                 }
 
               Ptr<PacketBurst> pktBurstCopy = p->Copy ();
-              Ptr<Object> netDevObj = (*rxPhyIterator)->GetDevice ();
-              if (netDevObj)
+              Ptr<NetDevice> netDev = (*rxPhyIterator)->GetDevice ();
+              if (netDev)
                 {
                   // the receiver has a NetDevice, so we expect that it is attached to a Node
-                  uint32_t dstNode =  netDevObj->GetObject<NetDevice> ()->GetNode ()->GetId ();
+                  uint32_t dstNode =  netDev->GetNode ()->GetId ();
                   Simulator::ScheduleWithContext (dstNode, delay, &MultiModelSpectrumChannel::StartRx, this,
                                                   pktBurstCopy, rxPowerSpectrum, st, duration, *rxPhyIterator);
                 }
@@ -337,7 +337,7 @@ MultiModelSpectrumChannel::GetNDevices (void) const
 Ptr<NetDevice>
 MultiModelSpectrumChannel::GetDevice (uint32_t i) const
 {
-  return m_phyVector.at (i)->GetDevice ()->GetObject<NetDevice> ();
+  return m_phyVector.at (i)->GetDevice ();
 }
 
 
diff --git a/src/spectrum/model/single-model-spectrum-channel.cc b/src/spectrum/model/single-model-spectrum-channel.cc
index 0af9aedcb..fa5d16566 100644
--- a/src/spectrum/model/single-model-spectrum-channel.cc
+++ b/src/spectrum/model/single-model-spectrum-channel.cc
@@ -116,7 +116,7 @@ SingleModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> txP
 
 
 
-  Ptr<MobilityModel> senderMobility = txPhy->GetMobility ()->GetObject<MobilityModel> ();
+  Ptr<MobilityModel> senderMobility = txPhy->GetMobility ();
 
   for (PhyList::const_iterator rxPhyIterator = m_phyList.begin ();
        rxPhyIterator != m_phyList.end ();
@@ -127,7 +127,7 @@ SingleModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> txP
           Ptr <SpectrumValue> rxPsd = Copy<SpectrumValue> (txPsd);
           Time delay  = MicroSeconds (0);
 
-          Ptr<MobilityModel> receiverMobility = (*rxPhyIterator)->GetMobility ()->GetObject<MobilityModel> ();
+          Ptr<MobilityModel> receiverMobility = (*rxPhyIterator)->GetMobility ();
 
           if (senderMobility && receiverMobility)
             {
@@ -155,11 +155,11 @@ SingleModelSpectrumChannel::StartTx (Ptr<PacketBurst> p, Ptr <SpectrumValue> txP
             }
 
           Ptr<PacketBurst> pktBurstCopy = p->Copy ();
-          Ptr<Object> netDevObj = (*rxPhyIterator)->GetDevice ();
-          if (netDevObj)
+          Ptr<NetDevice> netDev = (*rxPhyIterator)->GetDevice ();
+          if (netDev)
             {
               // the receiver has a NetDevice, so we expect that it is attached to a Node
-              uint32_t dstNode =  netDevObj->GetObject<NetDevice> ()->GetNode ()->GetId ();
+              uint32_t dstNode =  netDev->GetNode ()->GetId ();
               Simulator::ScheduleWithContext (dstNode, delay, &SingleModelSpectrumChannel::StartRx, this,
                                               pktBurstCopy, rxPsd, st, duration, *rxPhyIterator);
             }
diff --git a/src/spectrum/model/spectrum-analyzer.cc b/src/spectrum/model/spectrum-analyzer.cc
index 98d29c729..9962efc47 100644
--- a/src/spectrum/model/spectrum-analyzer.cc
+++ b/src/spectrum/model/spectrum-analyzer.cc
@@ -89,14 +89,14 @@ SpectrumAnalyzer::GetTypeId (void)
 
 
 
-Ptr<Object>
+Ptr<NetDevice>
 SpectrumAnalyzer::GetDevice ()
 {
   return m_netDevice;
 }
 
 
-Ptr<Object>
+Ptr<MobilityModel>
 SpectrumAnalyzer::GetMobility ()
 {
   return m_mobility;
@@ -110,7 +110,7 @@ SpectrumAnalyzer::GetRxSpectrumModel () const
 }
 
 void
-SpectrumAnalyzer::SetDevice (Ptr<Object> d)
+SpectrumAnalyzer::SetDevice (Ptr<NetDevice> d)
 {
   NS_LOG_FUNCTION (this << d);
   m_netDevice = d;
@@ -118,7 +118,7 @@ SpectrumAnalyzer::SetDevice (Ptr<Object> d)
 
 
 void
-SpectrumAnalyzer::SetMobility (Ptr<Object> m)
+SpectrumAnalyzer::SetMobility (Ptr<MobilityModel> m)
 {
   NS_LOG_FUNCTION (this << m);
   m_mobility = m;
diff --git a/src/spectrum/model/spectrum-analyzer.h b/src/spectrum/model/spectrum-analyzer.h
index 42d5cd8c4..decfdfa99 100644
--- a/src/spectrum/model/spectrum-analyzer.h
+++ b/src/spectrum/model/spectrum-analyzer.h
@@ -53,10 +53,10 @@ public:
 
 // inherited from SpectrumPhy
   void SetChannel (Ptr<SpectrumChannel> c);
-  void SetMobility (Ptr<Object> m);
-  void SetDevice (Ptr<Object> d);
-  Ptr<Object> GetMobility ();
-  Ptr<Object> GetDevice ();
+  void SetMobility (Ptr<MobilityModel> m);
+  void SetDevice (Ptr<NetDevice> d);
+  Ptr<MobilityModel> GetMobility ();
+  Ptr<NetDevice> GetDevice ();
   Ptr<const SpectrumModel> GetRxSpectrumModel () const;
   void StartRx (Ptr<PacketBurst> pb, Ptr <const SpectrumValue> rxPowerSpectralDensity, SpectrumType st, Time duration);
 
@@ -86,8 +86,8 @@ protected:
   void DoDispose ();
 
 private:
-  Ptr<Object> m_mobility;
-  Ptr<Object> m_netDevice;
+  Ptr<MobilityModel> m_mobility;
+  Ptr<NetDevice> m_netDevice;
   Ptr<SpectrumChannel> m_channel;
 
   virtual void GenerateReport ();
diff --git a/src/spectrum/model/spectrum-phy.h b/src/spectrum/model/spectrum-phy.h
index 4271f764a..99563432e 100644
--- a/src/spectrum/model/spectrum-phy.h
+++ b/src/spectrum/model/spectrum-phy.h
@@ -54,28 +54,28 @@ public:
    *
    * @param d the NetDevice instance
    */
-  virtual void SetDevice (Ptr<Object> d) = 0;
+  virtual void SetDevice (Ptr<NetDevice> d) = 0;
 
   /**
    * get the associated NetDevice instance
    *
    * @return a Ptr to the associated NetDevice instance
    */
-  virtual Ptr<Object> GetDevice () = 0;
+  virtual Ptr<NetDevice> GetDevice () = 0;
 
   /**
    * Set the mobility model associated with this device.
    *
    * @param m the mobility model
    */
-  virtual void SetMobility (Ptr<Object> m) = 0;
+  virtual void SetMobility (Ptr<MobilityModel> m) = 0;
 
   /**
    * get the associated MobilityModel instance
    *
    * @return a Ptr to the associated NetDevice instance
    */
-  virtual Ptr<Object> GetMobility () = 0;
+  virtual Ptr<MobilityModel> GetMobility () = 0;
 
 
   /**
diff --git a/src/spectrum/model/waveform-generator.cc b/src/spectrum/model/waveform-generator.cc
index 2d2c70b92..fb4874d09 100644
--- a/src/spectrum/model/waveform-generator.cc
+++ b/src/spectrum/model/waveform-generator.cc
@@ -89,14 +89,14 @@ WaveformGenerator::GetTypeId (void)
 
 
 
-Ptr<Object>
+Ptr<NetDevice>
 WaveformGenerator::GetDevice ()
 {
   return m_netDevice;
 }
 
 
-Ptr<Object>
+Ptr<MobilityModel>
 WaveformGenerator::GetMobility ()
 {
   return m_mobility;
@@ -111,14 +111,14 @@ WaveformGenerator::GetRxSpectrumModel () const
 }
 
 void
-WaveformGenerator::SetDevice (Ptr<Object> d)
+WaveformGenerator::SetDevice (Ptr<NetDevice> d)
 {
   m_netDevice = d;
 }
 
 
 void
-WaveformGenerator::SetMobility (Ptr<Object> m)
+WaveformGenerator::SetMobility (Ptr<MobilityModel> m)
 {
   m_mobility = m;
 }
diff --git a/src/spectrum/model/waveform-generator.h b/src/spectrum/model/waveform-generator.h
index 7b43c442f..52fd896a2 100644
--- a/src/spectrum/model/waveform-generator.h
+++ b/src/spectrum/model/waveform-generator.h
@@ -56,10 +56,10 @@ public:
 
   // inherited from SpectrumPhy
   void SetChannel (Ptr<SpectrumChannel> c);
-  void SetMobility (Ptr<Object> m);
-  void SetDevice (Ptr<Object> d);
-  Ptr<Object> GetMobility ();
-  Ptr<Object> GetDevice ();
+  void SetMobility (Ptr<MobilityModel> m);
+  void SetDevice (Ptr<NetDevice> d);
+  Ptr<MobilityModel> GetMobility ();
+  Ptr<NetDevice> GetDevice ();
   Ptr<const SpectrumModel> GetRxSpectrumModel () const;
   void StartRx (Ptr<PacketBurst> p, Ptr <const SpectrumValue> rxPsd, SpectrumType st, Time duration);
 
@@ -129,8 +129,8 @@ public:
 private:
   virtual void DoDispose (void);
 
-  Ptr<Object> m_mobility;
-  Ptr<Object> m_netDevice;
+  Ptr<MobilityModel> m_mobility;
+  Ptr<NetDevice> m_netDevice;
   Ptr<SpectrumChannel> m_channel;
 
   virtual void GenerateWaveform ();