diff --git a/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h b/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
index bc94c5c24b3..c600b7ac484 100644
--- a/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
+++ b/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
@@ -33,6 +33,8 @@
 #define DEBUG_STAR   0
 #define DEBUG_SIDE_OF_SPHERE   0
 
+CGAL_BEGIN_NAMESPACE
+
 template < class Gt, class Tds>
 class Regular_triangulation_3 : public Triangulation_3<Gt,Tds>
 {
@@ -546,4 +548,6 @@ public:
 
 // +++  Determination de la region en conflit  +++ //
 
+CGAL_END_NAMESPACE
+
 #endif CGAL_REGULAR_TRIANGULATION_3_H