Index: boost/date_time/date_formatting.hpp
===================================================================
--- boost/date_time/date_formatting.hpp	(revision 68583)
+++ boost/date_time/date_formatting.hpp	(working copy)
@@ -79,7 +79,13 @@
     {
       typedef typename ymd_type::month_type month_type;
       std::basic_ostringstream<charT> ss;
+
+      // Temporarily switch to classic locale to prevent possible formatting
+      // of year with comma or other character (for example 2,008).
+      ss.imbue(std::locale::classic());
       ss << ymd.year;
+      ss.imbue(std::locale());
+
       if (format_type::has_date_sep_chars()) {
         ss << format_type::month_sep_char();
       }