diff --git a/STL_Extension/doc/STL_Extension/CGAL/In_place_list.h b/STL_Extension/doc/STL_Extension/CGAL/In_place_list.h
index 6ce33c5bd9d..d5dc49c9d13 100644
--- a/STL_Extension/doc/STL_Extension/CGAL/In_place_list.h
+++ b/STL_Extension/doc/STL_Extension/CGAL/In_place_list.h
@@ -723,7 +723,7 @@ void unique();
 /*!
 merges the list `ipl2`
 into the list `ipl` and `ipl2` becomes empty. It is stable.
-\pre Both lists are increasingly sorted. A suitable `operator<` for the type `T`.
+\pre Both lists are sorted in increasing order by means of a suitable `operator<` for the type `T`.
 */
 void merge(In_place_list<T,bool>& ipl2);
 
diff --git a/STL_Extension/include/CGAL/In_place_list.h b/STL_Extension/include/CGAL/In_place_list.h
index 9c99f2e9a8f..246453abeab 100644
--- a/STL_Extension/include/CGAL/In_place_list.h
+++ b/STL_Extension/include/CGAL/In_place_list.h
@@ -575,14 +575,14 @@ public:
 
   void merge(Self& x);
   // merges the list x into the list `l' and x becomes empty. It is
-  // stable. Precondition: Both lists are increasingly sorted. A
-  // suitable `operator<' for the type T.
+  // stable. Precondition: Both lists are sorted in increasing order
+  // by means of a suitable `operator<` for the type `T`.
 
   template < class StrictWeakOrdering >
   void merge(Self& x, StrictWeakOrdering ord)
   // merges the list x into the list `l' and x becomes empty.
   // It is stable.
-  // Precondition: Both lists are increasingly sorted wrt. ord.
+  // Precondition: Both lists are sorted in increasing order wrt. `ord`.
   {
     iterator first1 = begin();
     iterator last1 = end();