diff --git a/include/boost/range/iterator_range_core.hpp b/include/boost/range/iterator_range_core.hpp
index 7664c2e..7ef7523 100755
--- a/include/boost/range/iterator_range_core.hpp
+++ b/include/boost/range/iterator_range_core.hpp
@@ -231,7 +231,7 @@ namespace boost
 
             difference_type size() const
             {
-                return std::distance(m_Begin, m_End);
+				return m_End - m_Begin;
             }
 
             bool empty() const