diff -up ppl-1.1/src/Dense_Row_defs.hh.orig ppl-1.1/src/Dense_Row_defs.hh
--- ppl-1.1/src/Dense_Row_defs.hh.orig	2014-04-29 13:08:10.516682937 -0300
+++ ppl-1.1/src/Dense_Row_defs.hh	2014-04-29 13:08:50.447684466 -0300
@@ -33,6 +33,7 @@ site: http://bugseng.com/products/ppl/ .
 #include <memory>
 #include <vector>
 #include <limits>
+#include <cstddef>
 
 #ifdef PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
 //! A finite sequence of coefficients.
@@ -433,7 +434,7 @@ public:
 
   typedef std::bidirectional_iterator_tag iterator_category;
   typedef Coefficient value_type;
-  typedef ptrdiff_t difference_type;
+  typedef std::ptrdiff_t difference_type;
   typedef value_type* pointer;
   typedef value_type& reference;
 
@@ -474,7 +475,7 @@ class Parma_Polyhedra_Library::Dense_Row
 public:
 
   typedef const Coefficient value_type;
-  typedef ptrdiff_t difference_type;
+  typedef std::ptrdiff_t difference_type;
   typedef value_type* pointer;
   typedef Coefficient_traits::const_reference reference;
 
diff -up ppl-1.1/src/Linear_Expression_Interface_defs.hh.orig ppl-1.1/src/Linear_Expression_Interface_defs.hh
--- ppl-1.1/src/Linear_Expression_Interface_defs.hh.orig	2014-04-29 13:08:17.337683198 -0300
+++ ppl-1.1/src/Linear_Expression_Interface_defs.hh	2014-04-29 13:08:40.999684104 -0300
@@ -32,6 +32,7 @@ site: http://bugseng.com/products/ppl/ .
 #include "Sparse_Row_types.hh"
 #include <vector>
 #include <set>
+#include <cstddef>
 
 #ifdef PPL_DOXYGEN_INCLUDE_IMPLEMENTATION_DETAILS
 //! A linear expression.
@@ -65,7 +66,7 @@ public:
   public:
     typedef std::bidirectional_iterator_tag iterator_category;
     typedef const Coefficient value_type;
-    typedef ptrdiff_t difference_type;
+    typedef std::ptrdiff_t difference_type;
     typedef value_type* pointer;
     typedef Coefficient_traits::const_reference reference;
 
diff -up ppl-1.1/src/CO_Tree_defs.hh.orig ppl-1.1/src/CO_Tree_defs.hh
--- ppl-1.1/src/CO_Tree_defs.hh.orig	2014-04-29 13:11:33.725690719 -0300
+++ ppl-1.1/src/CO_Tree_defs.hh	2014-04-29 13:11:55.943691569 -0300
@@ -28,6 +28,7 @@ site: http://bugseng.com/products/ppl/ .
 
 #include "Coefficient_defs.hh"
 #include <memory>
+#include <cstddef>
 
 #ifndef PPL_CO_TREE_EXTRA_DEBUG
 #ifdef PPL_ABI_BREAKING_EXTRA_DEBUG
@@ -159,7 +160,7 @@ public:
 
     typedef std::bidirectional_iterator_tag iterator_category;
     typedef const data_type value_type;
-    typedef ptrdiff_t difference_type;
+    typedef std::ptrdiff_t difference_type;
     typedef value_type* pointer;
     typedef data_type_const_reference reference;
 
@@ -314,7 +315,7 @@ public:
 
     typedef std::bidirectional_iterator_tag iterator_category;
     typedef data_type value_type;
-    typedef ptrdiff_t difference_type;
+    typedef std::ptrdiff_t difference_type;
     typedef value_type* pointer;
     typedef value_type& reference;
 
diff -up ppl-1.1/src/CO_Tree_inlines.hh.orig ppl-1.1/src/CO_Tree_inlines.hh
--- ppl-1.1/src/CO_Tree_inlines.hh.orig	2014-04-29 13:14:12.738696808 -0300
+++ ppl-1.1/src/CO_Tree_inlines.hh	2014-04-29 13:14:48.887698192 -0300
@@ -24,6 +24,8 @@ site: http://bugseng.com/products/ppl/ .
 #ifndef PPL_CO_Tree_inlines_hh
 #define PPL_CO_Tree_inlines_hh 1
 
+#include <cstddef>
+
 namespace Parma_Polyhedra_Library {
 
 inline dimension_type
@@ -31,7 +33,7 @@ CO_Tree::dfs_index(const_iterator itr) c
   PPL_ASSERT(itr.current_index != 0);
   PPL_ASSERT(itr.current_index >= indexes + 1);
   PPL_ASSERT(itr.current_index <= indexes + reserved_size);
-  const ptrdiff_t index = itr.current_index - indexes;
+  const std::ptrdiff_t index = itr.current_index - indexes;
   return static_cast<dimension_type>(index);
 }
 
@@ -40,7 +42,7 @@ CO_Tree::dfs_index(iterator itr) const {
   PPL_ASSERT(itr.current_index != 0);
   PPL_ASSERT(itr.current_index >= indexes + 1);
   PPL_ASSERT(itr.current_index <= indexes + reserved_size);
-  const ptrdiff_t index = itr.current_index - indexes;
+  const std::ptrdiff_t index = itr.current_index - indexes;
   return static_cast<dimension_type>(index);
 }
 
@@ -772,7 +774,7 @@ CO_Tree::tree_iterator::follow_left_chil
   p -= (offset - 1);
   while (*p == unused_index)
     ++p;
-  const ptrdiff_t distance = p - tree.indexes;
+  const std::ptrdiff_t distance = p - tree.indexes;
   PPL_ASSERT(distance >= 0);
   i = static_cast<dimension_type>(distance);
   offset = least_significant_one_mask(i);
@@ -787,7 +789,7 @@ CO_Tree::tree_iterator::follow_right_chi
   p += (offset - 1);
   while (*p == unused_index)
     --p;
-  const ptrdiff_t distance = p - tree.indexes;
+  const std::ptrdiff_t distance = p - tree.indexes;
   PPL_ASSERT(distance >= 0);
   i = static_cast<dimension_type>(distance);
   offset = least_significant_one_mask(i);
diff -up ppl-1.1/src/Linear_Expression_defs.hh.orig ppl-1.1/src/Linear_Expression_defs.hh
--- ppl-1.1/src/Linear_Expression_defs.hh.orig	2014-04-29 13:15:39.793700141 -0300
+++ ppl-1.1/src/Linear_Expression_defs.hh	2014-04-29 13:16:07.464701201 -0300
@@ -51,6 +51,7 @@ site: http://bugseng.com/products/ppl/ .
 
 #include "Linear_Expression_Interface_defs.hh"
 #include "Variable_defs.hh"
+#include <cstddef>
 
 namespace Parma_Polyhedra_Library {
 
@@ -381,7 +382,7 @@ public:
   public:
     typedef std::bidirectional_iterator_tag iterator_category;
     typedef const Coefficient value_type;
-    typedef ptrdiff_t difference_type;
+    typedef std::ptrdiff_t difference_type;
     typedef value_type* pointer;
     typedef Coefficient_traits::const_reference reference;
 
diff -up ppl-1.1/src/CO_Tree.cc.orig ppl-1.1/src/CO_Tree.cc
--- ppl-1.1/src/CO_Tree.cc.orig	2014-04-29 13:19:37.192709232 -0300
+++ ppl-1.1/src/CO_Tree.cc	2014-04-29 13:19:58.000710029 -0300
@@ -954,7 +954,7 @@ PPL::CO_Tree
     --subtree_size;
   }
 
-  const ptrdiff_t distance = first_unused_index - indexes;
+  const std::ptrdiff_t distance = first_unused_index - indexes;
   PPL_ASSERT(distance >= 0);
   return static_cast<dimension_type>(distance);
 }
diff -up ppl-1.1/src/Constraint_System_defs.hh.orig ppl-1.1/src/Constraint_System_defs.hh
--- ppl-1.1/src/Constraint_System_defs.hh.orig	2014-04-29 13:30:05.530733294 -0300
+++ ppl-1.1/src/Constraint_System_defs.hh	2014-04-29 13:30:27.167734122 -0300
@@ -37,6 +37,7 @@ site: http://bugseng.com/products/ppl/ .
 #include "termination_types.hh"
 #include <iterator>
 #include <iosfwd>
+#include <cstddef>
 
 namespace Parma_Polyhedra_Library {
 
@@ -609,7 +610,7 @@ for (Constraint_System::const_iterator i
 class Parma_Polyhedra_Library::Constraint_System_const_iterator
   : public std::iterator<std::forward_iterator_tag,
                          Constraint,
-                         ptrdiff_t,
+                         std::ptrdiff_t,
                          const Constraint*,
                          const Constraint&> {
 public:
diff -up ppl-1.1/src/Congruence_System_defs.hh.orig ppl-1.1/src/Congruence_System_defs.hh
--- ppl-1.1/src/Congruence_System_defs.hh.orig	2014-04-29 13:33:56.927742155 -0300
+++ ppl-1.1/src/Congruence_System_defs.hh	2014-04-29 13:34:15.535742867 -0300
@@ -33,6 +33,7 @@ site: http://bugseng.com/products/ppl/ .
 #include "Congruence_defs.hh"
 #include "Constraint_System_types.hh"
 #include <iosfwd>
+#include <cstddef>
 
 namespace Parma_Polyhedra_Library {
 
@@ -249,7 +250,7 @@ public:
   class const_iterator
     : public std::iterator<std::forward_iterator_tag,
                            Congruence,
-                           ptrdiff_t,
+                           std::ptrdiff_t,
                            const Congruence*,
                            const Congruence&> {
   public:
diff -up ppl-1.1/src/Generator_System_defs.hh.orig ppl-1.1/src/Generator_System_defs.hh
--- ppl-1.1/src/Generator_System_defs.hh.orig	2014-04-29 13:44:30.122766402 -0300
+++ ppl-1.1/src/Generator_System_defs.hh	2014-04-29 13:44:48.167767093 -0300
@@ -33,6 +33,7 @@ site: http://bugseng.com/products/ppl/ .
 #include "Poly_Con_Relation_defs.hh"
 #include "Polyhedron_types.hh"
 #include <iosfwd>
+#include <cstddef>
 
 namespace Parma_Polyhedra_Library {
 
@@ -679,7 +680,7 @@ copy(gs.begin(), gs.end(), ostream_itera
 class Parma_Polyhedra_Library::Generator_System_const_iterator
   : public std::iterator<std::forward_iterator_tag,
         Generator,
-        ptrdiff_t,
+        std::ptrdiff_t,
         const Generator*,
         const Generator&> {
 public:
diff -up ppl-1.1/src/Grid_Generator_System_defs.hh.orig ppl-1.1/src/Grid_Generator_System_defs.hh
--- ppl-1.1/src/Grid_Generator_System_defs.hh.orig	2014-04-29 13:45:26.073768544 -0300
+++ ppl-1.1/src/Grid_Generator_System_defs.hh	2014-04-29 13:45:42.535769175 -0300
@@ -31,6 +31,7 @@ site: http://bugseng.com/products/ppl/ .
 #include "Variables_Set_types.hh"
 #include "Polyhedron_types.hh"
 #include <iosfwd>
+#include <cstddef>
 
 namespace Parma_Polyhedra_Library {
 
@@ -277,7 +278,7 @@ public:
   class const_iterator
     : public std::iterator<std::forward_iterator_tag,
                            Grid_Generator,
-                           ptrdiff_t,
+                           std::ptrdiff_t,
                            const Grid_Generator*,
                            const Grid_Generator&> {
   public: