Index: boost/iterator/transform_iterator.hpp
===================================================================
--- boost/iterator/transform_iterator.hpp	(revision 61317)
+++ boost/iterator/transform_iterator.hpp	(working copy)
@@ -14,6 +14,7 @@
 #include <boost/iterator/iterator_categories.hpp>
 #include <boost/mpl/not.hpp>
 #include <boost/mpl/bool.hpp>
+#include <boost/optional.hpp>
 #include <boost/type_traits/function_traits.hpp>
 #include <boost/type_traits/is_const.hpp>
 #include <boost/type_traits/is_class.hpp>
@@ -130,15 +131,15 @@
    {}
 
     UnaryFunc functor() const
-      { return m_f; }
+      { return *m_f; }
 
   private:
     typename super_t::reference dereference() const
-    { return m_f(*this->base()); }
+    { return (*m_f)(*this->base()); }
 
     // Probably should be the initial base class so it can be
     // optimized away via EBO if it is an empty class.
-    UnaryFunc m_f;
+    boost::optional<UnaryFunc> m_f;
   };
 
   template <class UnaryFunc, class Iterator>