diff --git a/include/boost/regex/v4/regex_format.hpp b/include/boost/regex/v4/regex_format.hpp
index 872fbec2..15b29707 100644
--- a/include/boost/regex/v4/regex_format.hpp
+++ b/include/boost/regex/v4/regex_format.hpp
@@ -563,6 +563,12 @@ class string_out_iterator
 {
    S* out;
 public:
+   typedef typename S::difference_type difference_type;
+   typedef typename S::value_type value_type;
+   typedef typename S::pointer pointer;
+   typedef typename S::reference reference;
+   typedef typename std::output_iterator_tag iterator_category;
+
    string_out_iterator(S& s) : out(&s) {}
    string_out_iterator& operator++() { return *this; }
    string_out_iterator& operator++(int) { return *this; }