diff --git a/include/boost/iterator/permutation_iterator.hpp b/include/boost/iterator/permutation_iterator.hpp
index eb15a5a..73447a3 100644
--- a/include/boost/iterator/permutation_iterator.hpp
+++ b/include/boost/iterator/permutation_iterator.hpp
@@ -5,8 +5,8 @@
 // accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
-#ifndef BOOST_PERMUTATION_ITERATOR_HPP
-#define BOOST_PERMUTATION_ITERATOR_HPP
+#ifndef BOOST_ITERATOR_PERMUTATION_ITERATOR_HPP_INCLUDED_
+#define BOOST_ITERATOR_PERMUTATION_ITERATOR_HPP_INCLUDED_
 
 #include <iterator>
 
@@ -17,54 +17,62 @@
 namespace boost {
 namespace iterators {
 
-template< class ElementIterator
-        , class IndexIterator>
-class permutation_iterator
-  : public iterator_adaptor<
-             permutation_iterator<ElementIterator, IndexIterator>
-           , IndexIterator, typename std::iterator_traits<ElementIterator>::value_type
-           , use_default, typename std::iterator_traits<ElementIterator>::reference>
+template< typename ElementIterator, typename IndexIterator >
+class permutation_iterator :
+    public iterator_adaptor<
+        permutation_iterator< ElementIterator, IndexIterator >,
+        IndexIterator,
+        typename std::iterator_traits< ElementIterator >::value_type,
+        use_default,
+        typename std::iterator_traits< ElementIterator >::reference
+    >
 {
-  typedef iterator_adaptor<
-            permutation_iterator<ElementIterator, IndexIterator>
-          , IndexIterator, typename std::iterator_traits<ElementIterator>::value_type
-          , use_default, typename std::iterator_traits<ElementIterator>::reference> super_t;
-
-  friend class iterator_core_access;
-
-public:
-  permutation_iterator() : m_elt_iter() {}
-
-  explicit permutation_iterator(ElementIterator x, IndexIterator y)
-      : super_t(y), m_elt_iter(x) {}
-
-  template<class OtherElementIterator, class OtherIndexIterator>
-  permutation_iterator(
-      permutation_iterator<OtherElementIterator, OtherIndexIterator> const& r
-      , typename enable_if_convertible<OtherElementIterator, ElementIterator>::type* = 0
-      , typename enable_if_convertible<OtherIndexIterator, IndexIterator>::type* = 0
-      )
-    : super_t(r.base()), m_elt_iter(r.m_elt_iter)
-  {}
+    friend class iterator_core_access;
+    template< typename, typename >
+    friend class permutation_iterator;
 
 private:
-    typename super_t::reference dereference() const
-        { return *(m_elt_iter + *this->base()); }
+    using super_t = iterator_adaptor<
+        permutation_iterator< ElementIterator, IndexIterator >,
+        IndexIterator,
+        typename std::iterator_traits< ElementIterator >::value_type,
+        use_default,
+        typename std::iterator_traits< ElementIterator >::reference
+    >;
 
-#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
-    template <class,class> friend class permutation_iterator;
-#else
- public:
-#endif
+public:
+    permutation_iterator() :
+        m_elt_iter()
+    {}
+
+    explicit permutation_iterator(ElementIterator x, IndexIterator y) :
+        super_t(y),
+        m_elt_iter(x)
+    {}
+
+    template<
+        typename OtherElementIterator,
+        typename OtherIndexIterator,
+        typename = enable_if_convertible_t< OtherElementIterator, ElementIterator >,
+        typename = enable_if_convertible_t< OtherIndexIterator, IndexIterator >
+    >
+    permutation_iterator(permutation_iterator< OtherElementIterator, OtherIndexIterator > const& r) :
+        super_t(r.base()),
+        m_elt_iter(r.m_elt_iter)
+    {}
+
+private:
+    typename super_t::reference dereference() const { return *(m_elt_iter + *this->base()); }
+
+private:
     ElementIterator m_elt_iter;
 };
 
 
-template <class ElementIterator, class IndexIterator>
-inline permutation_iterator<ElementIterator, IndexIterator>
-make_permutation_iterator( ElementIterator e, IndexIterator i )
+template< typename ElementIterator, typename IndexIterator >
+inline permutation_iterator< ElementIterator, IndexIterator > make_permutation_iterator(ElementIterator e, IndexIterator i)
 {
-    return permutation_iterator<ElementIterator, IndexIterator>( e, i );
+    return permutation_iterator< ElementIterator, IndexIterator >(e, i);
 }
 
 } // namespace iterators
@@ -74,4 +82,4 @@ using iterators::make_permutation_iterator;
 
 } // namespace boost
 
-#endif
+#endif // BOOST_ITERATOR_PERMUTATION_ITERATOR_HPP_INCLUDED_