Index: boost/iostreams/code_converter.hpp
===================================================================
--- boost/iostreams/code_converter.hpp	(revision 84007)
+++ boost/iostreams/code_converter.hpp	(working copy)
@@ -393,7 +393,8 @@
 
         switch (result) {
         case std::codecvt_base::partial:
-            partial = true; // Fall through.
+            partial = true;
+            BOOST_FALLTHROUGH;
         case std::codecvt_base::ok:
             total = static_cast<std::streamsize>(nint - s);
             break;