diff --git a/include/boost/exception/detail/object_hex_dump.hpp b/include/boost/exception/detail/object_hex_dump.hpp
index f535944..75a4179 100644
--- a/include/boost/exception/detail/object_hex_dump.hpp
+++ b/include/boost/exception/detail/object_hex_dump.hpp
@@ -11,6 +11,7 @@
 #include <ios>
 #include <string>
 #include <sstream>
+#include <cstdlib>
 
 namespace
 boost
@@ -21,11 +22,11 @@ boost
         template <class T>
         inline
         std::string
-        object_hex_dump( T const & x, size_t max_size=16 )
+        object_hex_dump( T const & x, std::size_t max_size=16 )
             {
             std::ostringstream s;
             s << "type: " << type_name<T>() << ", size: " << sizeof(T) << ", dump: ";
-            size_t n=sizeof(T)>max_size?max_size:sizeof(T);
+            std::size_t n=sizeof(T)>max_size?max_size:sizeof(T);
             s.fill('0');
             s.width(2);
             unsigned char const * b=reinterpret_cast<unsigned char const *>(&x);