diff --git a/include/osgShadow/MinimalShadowMap b/include/osgShadow/MinimalShadowMap
index 6efac78e4..bec349f41 100644
--- a/include/osgShadow/MinimalShadowMap
+++ b/include/osgShadow/MinimalShadowMap
@@ -136,8 +136,8 @@ class OSGSHADOW_EXPORT MinimalShadowMap : public StandardShadowMap
                 const osg::BoundingBox &bb =
                 osg::BoundingBox(-1,-1,-1,1,1,1) );
 
-            osg::BoundingBox computeScenePolytopeBounds
-                ( const osg::Matrix & m = *(osg::Matrix*)(NULL) );
+            osg::BoundingBox computeScenePolytopeBounds();
+            osg::BoundingBox computeScenePolytopeBounds(const osg::Matrix& m);
 
             // Utility methods for adjusting projection matrices
 
diff --git a/src/osgShadow/MinimalShadowMap.cpp b/src/osgShadow/MinimalShadowMap.cpp
index 52e349807..49ad1adf7 100644
--- a/src/osgShadow/MinimalShadowMap.cpp
+++ b/src/osgShadow/MinimalShadowMap.cpp
@@ -353,17 +353,22 @@ void MinimalShadowMap::ViewData::cutScenePolytope
         _sceneReceivingShadowPolytope.clear();
 }
 
-osg::BoundingBox
-    MinimalShadowMap::ViewData::computeScenePolytopeBounds( const osg::Matrix & m )
+osg::BoundingBox MinimalShadowMap::ViewData::computeScenePolytopeBounds()
 {
     osg::BoundingBox bb;
 
-    if( &m )
-        for( unsigned i = 0; i < _sceneReceivingShadowPolytopePoints.size(); ++i )
-            bb.expandBy( _sceneReceivingShadowPolytopePoints[i] * m );
-    else
-        for( unsigned i = 0; i < _sceneReceivingShadowPolytopePoints.size(); ++i )
-            bb.expandBy( _sceneReceivingShadowPolytopePoints[i] );
+    for( unsigned i = 0; i < _sceneReceivingShadowPolytopePoints.size(); ++i )
+        bb.expandBy( _sceneReceivingShadowPolytopePoints[i] );
+
+    return bb;
+}
+
+osg::BoundingBox MinimalShadowMap::ViewData::computeScenePolytopeBounds( const osg::Matrix & m )
+{
+    osg::BoundingBox bb;
+
+    for( unsigned i = 0; i < _sceneReceivingShadowPolytopePoints.size(); ++i )
+        bb.expandBy( _sceneReceivingShadowPolytopePoints[i] * m );
 
     return bb;
 }