Index: boost/date_time/posix_time/time_formatters.hpp
===================================================================
--- boost/date_time/posix_time/time_formatters.hpp	(revision 68583)
+++ boost/date_time/posix_time/time_formatters.hpp	(working copy)
@@ -144,6 +144,9 @@
         date_time::absolute_value(td.fractional_seconds());
 #endif
       if (frac_sec != 0) {
+        // Temporarily switch to classic locale to prevent possible formatting
+        // of frac_sec with comma or other character (for example 123,456).
+        ss.imbue(std::locale::classic());
         ss  << "." << std::setw(time_duration::num_fractional_digits())
             << std::setfill(fill_char)
 
@@ -153,6 +156,7 @@
 #else
         << frac_sec;
 #endif
+        ss.imbue(std::locale());
       }
     }// else
     return ss.str();