diff --git a/STL_Extension/include/CGAL/Concatenate_iterator.h b/STL_Extension/include/CGAL/Concatenate_iterator.h
index 17a7b92ef8d..0e1d984f3d9 100644
--- a/STL_Extension/include/CGAL/Concatenate_iterator.h
+++ b/STL_Extension/include/CGAL/Concatenate_iterator.h
@@ -54,7 +54,7 @@ class Concatenate_iterator
 
 public:
   Concatenate_iterator() : e1_(), i1_(), b2_(), i2_() {}
-  
+
   Concatenate_iterator(It1 e1, It2 b2, It1 i1)
     : e1_(e1), i1_(i1), b2_(b2), i2_(b2) {}