diff --git a/include/boost/range/algorithm_ext/is_sorted.hpp b/include/boost/range/algorithm_ext/is_sorted.hpp
index 3d1273a..3d00729 100755
--- a/include/boost/range/algorithm_ext/is_sorted.hpp
+++ b/include/boost/range/algorithm_ext/is_sorted.hpp
@@ -34,7 +34,7 @@ inline bool is_sorted(const SinglePassRange& rng)
     BOOST_RANGE_CONCEPT_ASSERT((SinglePassRangeConcept<const SinglePassRange>));
     BOOST_RANGE_CONCEPT_ASSERT((LessThanComparableConcept<BOOST_DEDUCED_TYPENAME
       range_value<const SinglePassRange>::type>));
-    return boost::detail::is_sorted(boost::begin(rng), boost::end(rng));
+    return ::boost::detail::is_sorted(boost::begin(rng), boost::end(rng));
 }
 
 /// \overload
@@ -45,7 +45,7 @@ inline bool is_sorted(const SinglePassRange& rng, BinaryPredicate pred)
     BOOST_RANGE_CONCEPT_ASSERT((BinaryPredicateConcept<BinaryPredicate,
       BOOST_DEDUCED_TYPENAME range_value<const SinglePassRange>::type,
       BOOST_DEDUCED_TYPENAME range_value<const SinglePassRange>::type>));
-    return boost::detail::is_sorted(boost::begin(rng), boost::end(rng), pred);
+    return ::boost::detail::is_sorted(boost::begin(rng), boost::end(rng), pred);
 }
 
     } // namespace range