Bradley-Meyers-MacBook-Air:boost-trunk bradleymeyer$ svn diff boost/multi_index/hashed_index.hpp 
Index: boost/multi_index/hashed_index.hpp
===================================================================
--- boost/multi_index/hashed_index.hpp	(revision 83051)
+++ boost/multi_index/hashed_index.hpp	(working copy)
@@ -1047,7 +1047,7 @@
   {
     if(n>max_load){
       size_type bc =(std::numeric_limits<size_type>::max)();
-      float     fbc=static_cast<float>(1+n/mlf);
+      float     fbc=static_cast<float>(1+n/static_cast<size_type>(mlf));
       if(bc>fbc)bc =static_cast<size_type>(fbc);
       unchecked_rehash(bc);
     }