diff --git a/include/osg/BoundingBox b/include/osg/BoundingBox
index f3e21e039..e6c5b4698 100644
--- a/include/osg/BoundingBox
+++ b/include/osg/BoundingBox
@@ -51,6 +51,12 @@ class BoundingBoxImpl
                  -FLT_MAX)
         {}
 
+        template<typename BT>
+        inline BoundingBoxImpl(const BoundingBoxImpl<BT>& bb) :
+            _min(bb._min),
+            _max(bb._max)
+        {}
+
         /** Creates a bounding box initialized to the given extents. */
         inline BoundingBoxImpl(value_type xmin, value_type ymin, value_type zmin,
                            value_type xmax, value_type ymax, value_type zmax) :
@@ -192,7 +198,8 @@ class BoundingBoxImpl
 
         /** Expands this bounding box to include the given sphere.
           * If this box is uninitialized, set it to include sh. */
-        void expandBy(const BoundingSphereImpl<VT>& sh)
+        template<typename BST>
+        void expandBy(const BoundingSphereImpl<BST>& sh)
         {
             if (!sh.valid()) return;
 
diff --git a/include/osg/BoundingSphere b/include/osg/BoundingSphere
index c0afdcf8f..eb93ac277 100644
--- a/include/osg/BoundingSphere
+++ b/include/osg/BoundingSphere
@@ -113,11 +113,13 @@ class BoundingSphereImpl
 
         /** Expands the sphere to encompass the given box. Repositions the
           * sphere center to minimize the radius increase. */
-        void expandBy(const BoundingBoxImpl<VT>& bb);
+        template<typename BBT>
+        void expandBy(const BoundingBoxImpl<BBT>& bb);
 
         /** Expands the sphere to encompass the given box. Does not
           * repositions the sphere center. */
-        void expandRadiusBy(const BoundingBoxImpl<VT>& bb);
+        template<typename BBT>
+        void expandRadiusBy(const BoundingBoxImpl<BBT>& bb);
 
         /** Returns true if v is within the sphere. */
         inline bool contains(const vec_type& v) const
@@ -138,12 +140,12 @@ class BoundingSphereImpl
 
 
 template<typename VT>
- template<typename vector_type>
+template<typename vector_type>
 void BoundingSphereImpl<VT>::expandBy(const vector_type& v)
 {
     if (valid())
     {
-        vec_type dv = v-_center;
+        vec_type dv = vec_type(v)-_center;
         value_type r = dv.length();
         if (r>_radius)
         {
@@ -160,12 +162,12 @@ void BoundingSphereImpl<VT>::expandBy(const vector_type& v)
 }
 
 template<typename VT>
- template<typename vector_type>
+template<typename vector_type>
 void BoundingSphereImpl<VT>::expandRadiusBy(const vector_type& v)
 {
     if (valid())
     {
-        value_type r = (v-_center).length();
+        value_type r = (vec_type(v)-_center).length();
         if (r>_radius) _radius = r;
         // else do nothing as vertex is within sphere.
     }
@@ -247,7 +249,8 @@ void BoundingSphereImpl<VT>::expandRadiusBy(const BoundingSphereImpl& sh)
 }
 
 template<typename VT>
-void BoundingSphereImpl<VT>::expandBy(const BoundingBoxImpl<VT>& bb)
+template<typename BBT>
+void BoundingSphereImpl<VT>::expandBy(const BoundingBoxImpl<BBT>& bb)
 {
     if (bb.valid())
     {
@@ -277,7 +280,8 @@ void BoundingSphereImpl<VT>::expandBy(const BoundingBoxImpl<VT>& bb)
 }
 
 template<typename VT>
-void BoundingSphereImpl<VT>::expandRadiusBy(const BoundingBoxImpl<VT>& bb)
+template<typename BBT>
+void BoundingSphereImpl<VT>::expandRadiusBy(const BoundingBoxImpl<BBT>& bb)
 {
     if (bb.valid())
     {