diff --git a/include/boost/smart_ptr/allocate_local_shared_array.hpp b/include/boost/smart_ptr/allocate_local_shared_array.hpp
index d472418..2c890ee 100644
--- a/include/boost/smart_ptr/allocate_local_shared_array.hpp
+++ b/include/boost/smart_ptr/allocate_local_shared_array.hpp
@@ -95,7 +95,7 @@ inline typename std::enable_if<is_bounded_array<T>::value,
 allocate_local_shared(const A& allocator)
 {
     enum {
-        count = extent<T>::value
+        count = std::extent<T>::value
     };
     typedef typename detail::sp_array_element<T>::type element;
     typedef typename allocator_rebind<A, element>::type other;
@@ -140,7 +140,7 @@ allocate_local_shared(const A& allocator,
     const typename remove_extent<T>::type& value)
 {
     enum {
-        count = extent<T>::value
+        count = std::extent<T>::value
     };
     typedef typename detail::sp_array_element<T>::type element;
     typedef typename allocator_rebind<A, element>::type other;
diff --git a/include/boost/smart_ptr/allocate_shared_array.hpp b/include/boost/smart_ptr/allocate_shared_array.hpp
index e7ec10f..4a2bf50 100644
--- a/include/boost/smart_ptr/allocate_shared_array.hpp
+++ b/include/boost/smart_ptr/allocate_shared_array.hpp
@@ -12,7 +12,6 @@ Distributed under the Boost Software License, Version 1.0.
 #include <boost/core/alloc_construct.hpp>
 #include <boost/core/first_scalar.hpp>
 #include <boost/smart_ptr/shared_ptr.hpp>
-#include <boost/type_traits/extent.hpp>
 #include <boost/type_traits/is_bounded_array.hpp>
 #include <boost/type_traits/is_unbounded_array.hpp>
 #include <boost/type_traits/remove_cv.hpp>
@@ -278,11 +277,11 @@ inline typename std::enable_if<is_bounded_array<T>::value, shared_ptr<T> >::type
 allocate_shared(const A& allocator)
 {
     enum {
-        count = extent<T>::value
+        count = std::extent<T>::value
     };
     typedef typename detail::sp_array_element<T>::type element;
     typedef typename allocator_rebind<A, element>::type other;
-    typedef detail::sp_size_array_state<other, extent<T>::value> state;
+    typedef detail::sp_size_array_state<other, std::extent<T>::value> state;
     typedef detail::sp_array_base<state> base;
     detail::sp_array_result<other, base> result(allocator, count);
     base* node = result.get();
@@ -317,11 +316,11 @@ allocate_shared(const A& allocator,
     const typename remove_extent<T>::type& value)
 {
     enum {
-        count = extent<T>::value
+        count = std::extent<T>::value
     };
     typedef typename detail::sp_array_element<T>::type element;
     typedef typename allocator_rebind<A, element>::type other;
-    typedef detail::sp_size_array_state<other, extent<T>::value> state;
+    typedef detail::sp_size_array_state<other, std::extent<T>::value> state;
     typedef detail::sp_array_base<state> base;
     detail::sp_array_result<other, base> result(allocator, count);
     base* node = result.get();
diff --git a/include/boost/smart_ptr/allocate_unique.hpp b/include/boost/smart_ptr/allocate_unique.hpp
index abc9f1e..9317f95 100644
--- a/include/boost/smart_ptr/allocate_unique.hpp
+++ b/include/boost/smart_ptr/allocate_unique.hpp
@@ -14,7 +14,6 @@ Distributed under the Boost Software License, Version 1.0.
 #include <boost/core/first_scalar.hpp>
 #include <boost/core/noinit_adaptor.hpp>
 #include <boost/core/pointer_traits.hpp>
-#include <boost/type_traits/extent.hpp>
 #include <boost/type_traits/is_array.hpp>
 #include <boost/type_traits/is_bounded_array.hpp>
 #include <boost/type_traits/is_unbounded_array.hpp>
@@ -408,7 +407,7 @@ inline typename std::enable_if<is_bounded_array<T>::value,
         alloc_deleter<T, A> > >::type
 allocate_unique(const A& alloc)
 {
-    detail::sp_alloc_make<T, A> c(alloc, extent<T>::value);
+    detail::sp_alloc_make<T, A> c(alloc, std::extent<T>::value);
     boost::alloc_construct_n(c.state(), boost::first_scalar(c.get()),
         detail::sp_alloc_size<T>::value);
     return c.release();
@@ -451,7 +450,7 @@ inline typename std::enable_if<is_bounded_array<T>::value,
 allocate_unique(const A& alloc,
     const typename remove_extent<T>::type& value)
 {
-    detail::sp_alloc_make<T, A> c(alloc, extent<T>::value);
+    detail::sp_alloc_make<T, A> c(alloc, std::extent<T>::value);
     boost::alloc_construct_n(c.state(), boost::first_scalar(c.get()),
         detail::sp_alloc_size<T>::value, boost::first_scalar(&value),
         detail::sp_alloc_size<typename remove_extent<T>::type>::value);