diff --git a/Packages/Triangulation_3/include/CGAL/Delaunay_triangulation_3.h b/Packages/Triangulation_3/include/CGAL/Delaunay_triangulation_3.h
index f444d15b9a7..afb2ecad1dd 100644
--- a/Packages/Triangulation_3/include/CGAL/Delaunay_triangulation_3.h
+++ b/Packages/Triangulation_3/include/CGAL/Delaunay_triangulation_3.h
@@ -78,7 +78,7 @@ public:
   Delaunay_triangulation_3(const Delaunay_triangulation_3<Gt,Tds> 
 				& tr)
     : Triangulation_3<Gt,Tds>(tr)
-    { CGAL_triangulation_postcondition( is_valid(true) );  }
+    { CGAL_triangulation_postcondition( is_valid() );  }
   
 #ifndef CGAL_CFG_NO_MEMBER_TEMPLATES
   template < class InputIterator >
diff --git a/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h b/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
index e9929f2976e..f134d41dd6f 100644
--- a/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
+++ b/Packages/Triangulation_3/include/CGAL/Regular_triangulation_3.h
@@ -62,7 +62,7 @@ public:
   Regular_triangulation_3(const Regular_triangulation_3<Gt,Tds> & rt)
       : Triangulation_3<Gt,Tds>(rt)
     { 
-      CGAL_triangulation_postcondition( is_valid(true) );  
+      CGAL_triangulation_postcondition( is_valid() );  
     }
   
 #ifndef CGAL_CFG_NO_MEMBER_TEMPLATES
diff --git a/Packages/Triangulation_3/include/CGAL/Triangulation_cell_base_3.h b/Packages/Triangulation_3/include/CGAL/Triangulation_cell_base_3.h
index db9a9d76ee2..7dd2b4df0a1 100644
--- a/Packages/Triangulation_3/include/CGAL/Triangulation_cell_base_3.h
+++ b/Packages/Triangulation_3/include/CGAL/Triangulation_cell_base_3.h
@@ -186,7 +186,7 @@ public:
   // the following trivial is_valid allows
   // the user of derived cell base classes 
   // to add their own purpose checking
-  bool is_valid(bool verbose, int level) const
+  bool is_valid(bool verbose = false, int level = 0) const
     {return true;}
 
 
diff --git a/Packages/Triangulation_3/include/CGAL/Triangulation_vertex_base_3.h b/Packages/Triangulation_3/include/CGAL/Triangulation_vertex_base_3.h
index e2dc5ce9cf9..f4e4b6ba393 100644
--- a/Packages/Triangulation_3/include/CGAL/Triangulation_vertex_base_3.h
+++ b/Packages/Triangulation_3/include/CGAL/Triangulation_vertex_base_3.h
@@ -81,7 +81,7 @@ public:
   // the following trivial is_valid allows
   // the user of derived cell base classes 
   // to add their own purpose checking
-  bool is_valid(bool verbose, int level) const
+  bool is_valid(bool verbose = false, int level = 0) const
   { 
     //return true; 
     return( cell() != NULL );