diff --git a/boost/polygon/point_3d_concept.hpp b/boost/polygon/point_3d_concept.hpp
index ab7afeb..f29075e 100644
--- a/boost/polygon/point_3d_concept.hpp
+++ b/boost/polygon/point_3d_concept.hpp
@@ -170,7 +170,7 @@ namespace boost { namespace polygon{
     typedef typename coordinate_traits<typename point_3d_traits<point_type_1>::coordinate_type>::coordinate_distance return_value;
     return_value pdist = (return_value)euclidean_distance(point1, point2, PROXIMAL);
     pdist *= pdist;
-    return sqrt((double)(distance_squared(point1, point2) + pdist));
+    return std::sqrt((double)(distance_squared(point1, point2) + pdist));
   }
   
   struct y_p3d_convolve : gtl_yes {};
diff --git a/boost/polygon/point_concept.hpp b/boost/polygon/point_concept.hpp
index 6e2ce0a..5e3e439 100644
--- a/boost/polygon/point_concept.hpp
+++ b/boost/polygon/point_concept.hpp
@@ -174,7 +174,7 @@ namespace boost { namespace polygon{
   typename point_distance_type<point_type_1>::type>::type
   euclidean_distance(const point_type_1& point1, const point_type_2& point2) {
     typedef typename point_traits<point_type_1>::coordinate_type Unit;
-    return sqrt((double)(distance_squared(point1, point2)));
+    return std::sqrt((double)(distance_squared(point1, point2)));
   }
   
   template <typename point_type_1, typename point_type_2>
diff --git a/boost/polygon/polygon_set_data.hpp b/boost/polygon/polygon_set_data.hpp
index bbddacf..5ca4bf9 100644
--- a/boost/polygon/polygon_set_data.hpp
+++ b/boost/polygon/polygon_set_data.hpp
@@ -637,7 +637,7 @@ namespace boost { namespace polygon {
         point_data<double> v;
         assign(v, normal1);
         double s2 = (v.x()*v.x()+v.y()*v.y());
-        double s = sqrt(s2)/resizing;
+        double s = std::sqrt(s2)/resizing;
         v = point_data<double>(v.x()/s,v.y()/s);
         point_data<T> curr_prev;
         if (prev_concave)
@@ -817,10 +817,10 @@ namespace boost { namespace polygon {
 
       // handle the case of adding an intersection point
       point_data<double> dn1( middle.y()-start.y(), start.x()-middle.x());
-      double size = sizing_distance/sqrt( dn1.x()*dn1.x()+dn1.y()*dn1.y());
+      double size = sizing_distance/std::sqrt( dn1.x()*dn1.x()+dn1.y()*dn1.y());
       dn1 = point_data<double>( dn1.x()*size, dn1.y()* size);
       point_data<double> dn2( end.y()-middle.y(), middle.x()-end.x());
-      size = sizing_distance/sqrt( dn2.x()*dn2.x()+dn2.y()*dn2.y());
+      size = sizing_distance/std::sqrt( dn2.x()*dn2.x()+dn2.y()*dn2.y());
       dn2 = point_data<double>( dn2.x()*size, dn2.y()* size);
       point_data<double> start_offset((start.x()+dn1.x()),(start.y()+dn1.y()));
       point_data<double> mid1_offset((middle.x()+dn1.x()),(middle.y()+dn1.y()));
diff --git a/boost/polygon/rectangle_concept.hpp b/boost/polygon/rectangle_concept.hpp
index e302b99..5d8a99e 100644
--- a/boost/polygon/rectangle_concept.hpp
+++ b/boost/polygon/rectangle_concept.hpp
@@ -919,7 +919,7 @@ namespace boost { namespace polygon{
                                                           typename is_point_concept<typename geometry_concept<point_type>::type>::type>::type,
                        typename rectangle_distance_type<rectangle_type>::type>::type 
   euclidean_distance(rectangle_type& lvalue, const point_type& rvalue) {
-    return sqrt((double)
+    return std::sqrt((double)
                 (square_euclidean_distance(lvalue, rvalue)));
   }
 
@@ -931,7 +931,7 @@ namespace boost { namespace polygon{
                        typename rectangle_distance_type<rectangle_type>::type>::type 
   euclidean_distance(const rectangle_type& lvalue, const rectangle_type_2& rvalue) {
     double val = (int)square_euclidean_distance(lvalue, rvalue);
-    return sqrt(val);
+    return std::sqrt(val);
   }
 
   struct y_r_mdist : gtl_yes {};