diff --git a/src/routing/olsr/olsr-agent-impl.cc b/src/routing/olsr/olsr-agent-impl.cc
index fb684bc9b..5d44ab5ec 100644
--- a/src/routing/olsr/olsr-agent-impl.cc
+++ b/src/routing/olsr/olsr-agent-impl.cc
@@ -643,9 +643,9 @@ OlsrAgentImpl::MprComputation()
 /// \return the corresponding main address.
 ///
 Ipv4Address
-OlsrAgentImpl::GetMainAddress (Ipv4Address iface_addr)
+OlsrAgentImpl::GetMainAddress (Ipv4Address iface_addr) const
 {
-  IfaceAssocTuple *tuple =
+  const IfaceAssocTuple *tuple =
     m_state.FindIfaceAssocTuple (iface_addr);
   
   if (tuple != NULL)
diff --git a/src/routing/olsr/olsr-agent-impl.h b/src/routing/olsr/olsr-agent-impl.h
index a708a3818..e781654af 100644
--- a/src/routing/olsr/olsr-agent-impl.h
+++ b/src/routing/olsr/olsr-agent-impl.h
@@ -102,7 +102,7 @@ protected:
 
   void MprComputation ();
   void RoutingTableComputation ();
-  Ipv4Address GetMainAddress (Ipv4Address iface_addr);
+  Ipv4Address GetMainAddress (Ipv4Address iface_addr) const;
 
   // Timer handlers
   Timer m_helloTimer;
diff --git a/src/routing/olsr/olsr-state.cc b/src/routing/olsr/olsr-state.cc
index 519e9633e..d4deaf172 100644
--- a/src/routing/olsr/olsr-state.cc
+++ b/src/routing/olsr/olsr-state.cc
@@ -400,6 +400,18 @@ OlsrState::FindIfaceAssocTuple (Ipv4Address const &ifaceAddr)
   return NULL;
 }
 
+const IfaceAssocTuple*
+OlsrState::FindIfaceAssocTuple (Ipv4Address const &ifaceAddr) const
+{
+  for (IfaceAssocSet::const_iterator it = m_ifaceAssocSet.begin ();
+       it != m_ifaceAssocSet.end (); it++)
+    {
+      if (it->ifaceAddr == ifaceAddr)
+        return &(*it);
+    }
+  return NULL;
+}
+
 void
 OlsrState::EraseIfaceAssocTuple (const IfaceAssocTuple &tuple)
 {
diff --git a/src/routing/olsr/olsr-state.h b/src/routing/olsr/olsr-state.h
index d7788a572..ad2c735fe 100644
--- a/src/routing/olsr/olsr-state.h
+++ b/src/routing/olsr/olsr-state.h
@@ -129,6 +129,7 @@ public:
     return m_ifaceAssocSet;
   }
   IfaceAssocTuple* FindIfaceAssocTuple (const Ipv4Address &ifaceAddr);
+  const IfaceAssocTuple* FindIfaceAssocTuple (const Ipv4Address &ifaceAddr) const;
   void EraseIfaceAssocTuple (const IfaceAssocTuple &tuple);
   void InsertIfaceAssocTuple (const IfaceAssocTuple &tuple);