diff --git a/bindings/python/mapnik_proj_transform.cpp b/bindings/python/mapnik_proj_transform.cpp
index 23f55aa1b..2da9ebb43 100644
--- a/bindings/python/mapnik_proj_transform.cpp
+++ b/bindings/python/mapnik_proj_transform.cpp
@@ -61,26 +61,16 @@ mapnik::coord2d backward_transform_c(mapnik::proj_transform& t, mapnik::coord2d
 
 mapnik::box2d<double> forward_transform_env(mapnik::proj_transform& t, mapnik::box2d<double> const & box)
 {
-    double minx = box.minx();
-    double miny = box.miny();
-    double maxx = box.maxx();
-    double maxy = box.maxy();
-    double z = 0.0;
-    t.forward(minx,miny,z);
-    t.forward(maxx,maxy,z);
-    return mapnik::box2d<double>(minx,miny,maxx,maxy);
+    mapnik::box2d<double> new_box = box;
+    t.forward(new_box);
+    return new_box;
 }
 
 mapnik::box2d<double> backward_transform_env(mapnik::proj_transform& t, mapnik::box2d<double> const & box)
 {
-    double minx = box.minx();
-    double miny = box.miny();
-    double maxx = box.maxx();
-    double maxy = box.maxy();
-    double z = 0.0;
-    t.backward(minx,miny,z);
-    t.backward(maxx,maxy,z);
-    return mapnik::box2d<double>(minx,miny,maxx,maxy);
+    mapnik::box2d<double> new_box = box;
+    t.backward(new_box);
+    return new_box;
 }   
 }
 
diff --git a/include/mapnik/proj_transform.hpp b/include/mapnik/proj_transform.hpp
index 78bfa3a5e..ce6920ea1 100644
--- a/include/mapnik/proj_transform.hpp
+++ b/include/mapnik/proj_transform.hpp
@@ -41,6 +41,8 @@ public:
     bool equal() const;
     bool forward (double& x, double& y , double& z) const;
     bool backward (double& x, double& y , double& z) const;
+    bool forward (box2d<double> & box) const;
+    bool backward (box2d<double> & box) const;
     mapnik::projection const& source() const;
     mapnik::projection const& dest() const;
         
diff --git a/src/proj_transform.cpp b/src/proj_transform.cpp
index 0783cf821..3868d6628 100644
--- a/src/proj_transform.cpp
+++ b/src/proj_transform.cpp
@@ -105,6 +105,37 @@ bool proj_transform::backward (double & x, double & y , double & z) const
     return true;
 }
 
+bool proj_transform::forward (box2d<double> & box) const
+{
+    if (is_source_equal_dest_)
+        return true;
+    double minx = box.minx();
+    double miny = box.miny();
+    double maxx = box.maxx();
+    double maxy = box.maxy();
+    double z = 0.0;
+    bool ok0 = forward(minx,miny,z);
+    bool ok1 = forward(maxx,maxy,z);
+    box.init(minx,miny,maxx,maxy);
+    return ok0 & ok1;
+} 
+        
+bool proj_transform::backward (box2d<double> & box) const
+{
+    if (is_source_equal_dest_)
+        return true;
+
+    double minx = box.minx();
+    double miny = box.miny();
+    double maxx = box.maxx();
+    double maxy = box.maxy();
+    double z = 0.0;
+    bool ok0 = backward(minx,miny,z);
+    bool ok1 = backward(maxx,maxy,z);
+    box.init(minx,miny,maxx,maxy);
+    return ok0 & ok1;
+}
+
 mapnik::projection const& proj_transform::source() const
 {
     return source_;