diff --git a/include/osg/Image b/include/osg/Image
index cdbfac39c..cb099feea 100644
--- a/include/osg/Image
+++ b/include/osg/Image
@@ -373,7 +373,7 @@ class OSG_EXPORT Image : public BufferData
         };
 
         /** method for hinting whether to enable or disable focus to images acting as front ends to interactive surfaces such as a vnc or browser window.  Return true if handled. */
-        virtual bool sendFocusHint(bool focus) { return false; }
+        virtual bool sendFocusHint(bool /*focus*/) { return false; }
 
         /** method for sending pointer events to images that are acting as front ends to interactive surfaces such as a vnc or browser window.  Return true if handled. */
         virtual bool sendPointerEvent(int /*x*/, int /*y*/, int /*buttonMask*/) { return false; }
diff --git a/include/osg/Observer b/include/osg/Observer
index c3d1155a2..9e0fa8761 100644
--- a/include/osg/Observer
+++ b/include/osg/Observer
@@ -64,7 +64,7 @@ class OSG_EXPORT ObserverSet : public osg::Referenced
     protected:
 
         ObserverSet(const ObserverSet& rhs): osg::Referenced(rhs) {}
-        ObserverSet& operator = (const ObserverSet& rhs) { return *this; }
+        ObserverSet& operator = (const ObserverSet& /*rhs*/) { return *this; }
         virtual ~ObserverSet();
 
         mutable OpenThreads::Mutex      _mutex;
diff --git a/include/osgTerrain/TerrainTechnique b/include/osgTerrain/TerrainTechnique
index 683e0876d..1b0d701cf 100644
--- a/include/osgTerrain/TerrainTechnique
+++ b/include/osgTerrain/TerrainTechnique
@@ -39,8 +39,8 @@ class OSGTERRAIN_EXPORT TerrainNeighbours
 
     protected:
 
-        TerrainNeighbours(const TerrainNeighbours& tn) {}
-        TerrainNeighbours& operator = (const TerrainNeighbours& rhs) { return *this; }
+        TerrainNeighbours(const TerrainNeighbours& /*tn*/) {}
+        TerrainNeighbours& operator = (const TerrainNeighbours& /*rhs*/) { return *this; }
 
         typedef std::set<TerrainTile*> Neighbours;