diff --git a/include/boost/throw_exception.hpp b/include/boost/throw_exception.hpp
index 1699a61..b8a2e49 100644
--- a/include/boost/throw_exception.hpp
+++ b/include/boost/throw_exception.hpp
@@ -25,6 +25,7 @@
 #include <boost/config.hpp>
 #include <boost/config/workaround.hpp>
 #include <exception>
+#include <cstddef>
 
 #if !defined( BOOST_EXCEPTION_DISABLE ) && defined( BOOST_BORLANDC ) && BOOST_WORKAROUND( BOOST_BORLANDC, BOOST_TESTED_AT(0x593) )
 # define BOOST_EXCEPTION_DISABLE
@@ -51,7 +52,7 @@ typedef char (&wrapexcept_s2)[ 2 ];
 template<class T> wrapexcept_s1 wrapexcept_is_convertible( T* );
 template<class T> wrapexcept_s2 wrapexcept_is_convertible( void* );
 
-template<class E, class B, int I = sizeof( wrapexcept_is_convertible<B>( static_cast< E* >( 0 ) ) ) > struct wrapexcept_add_base;
+template<class E, class B, std::size_t I = sizeof( wrapexcept_is_convertible<B>( static_cast< E* >( 0 ) ) ) > struct wrapexcept_add_base;
 
 template<class E, class B> struct wrapexcept_add_base<E, B, 1>
 {