diff --git a/src/helper/csma-helper.cc b/src/helper/csma-helper.cc
index bd4723b26..f941306c1 100644
--- a/src/helper/csma-helper.cc
+++ b/src/helper/csma-helper.cc
@@ -55,6 +55,7 @@ CsmaHelper::Build (const NodeContainer &c, Ptr<CsmaChannel> channel)
     {
       Ptr<Node> node = *i;
       Ptr<CsmaNetDevice> device = m_deviceFactory.Create<CsmaNetDevice> ();
+      device->SetAddress (Mac48Address::Allocate ());
       node->AddDevice (device);
       Ptr<Queue> queue = m_queueFactory.Create<Queue> ();
       device->AddQueue (queue);
diff --git a/src/helper/point-to-point-helper.cc b/src/helper/point-to-point-helper.cc
index 33f34979d..5a7570d80 100644
--- a/src/helper/point-to-point-helper.cc
+++ b/src/helper/point-to-point-helper.cc
@@ -48,10 +48,12 @@ PointToPointHelper::Build (Ptr<Node> a, Ptr<Node> b)
   NetDeviceContainer container;
 
   Ptr<PointToPointNetDevice> devA = CreateObject<PointToPointNetDevice> ();
+  devA->SetAddress (Mac48Address::Allocate ());
   a->AddDevice (devA);
   Ptr<Queue> queueA = m_queueFactory.Create<Queue> ();
   devA->AddQueue (queueA);
   Ptr<PointToPointNetDevice> devB = CreateObject<PointToPointNetDevice> ();
+  devB->SetAddress (Mac48Address::Allocate ());
   b->AddDevice (devB);
   Ptr<Queue> queueB = m_queueFactory.Create<Queue> ();
   devB->AddQueue (queueB);
diff --git a/src/helper/wifi-helper.cc b/src/helper/wifi-helper.cc
index d9b990574..76926b718 100644
--- a/src/helper/wifi-helper.cc
+++ b/src/helper/wifi-helper.cc
@@ -110,6 +110,7 @@ WifiHelper::Build (NodeContainer c, Ptr<WifiChannel> channel) const
       Ptr<WifiRemoteStationManager> manager = m_stationManager.Create<WifiRemoteStationManager> ();
       Ptr<WifiMac> mac = m_mac.Create<WifiMac> ();
       Ptr<WifiPhy> phy = m_phy.Create<WifiPhy> ();
+      mac->SetAddress (Mac48Address::Allocate ());
       device->SetMac (mac);
       device->SetPhy (phy);
       device->SetRemoteStationManager (manager);