diff --git a/include/boost/mpl/void.hpp b/include/boost/mpl/void.hpp
index 2f6c06b..f373ac1 100644
--- a/include/boost/mpl/void.hpp
+++ b/include/boost/mpl/void.hpp
@@ -7,11 +7,11 @@
 // Peter Dimov, Aleksey Gurtovoy
 //
 // Permission to use, copy, modify, distribute and sell this software
-// and its documentation for any purpose is hereby granted without fee, 
-// provided that the above copyright notice appears in all copies and 
-// that both the copyright notice and this permission notice appear in 
-// supporting documentation. No representations are made about the 
-// suitability of this software for any purpose. It is provided "as is" 
+// and its documentation for any purpose is hereby granted without fee,
+// provided that the above copyright notice appears in all copies and
+// that both the copyright notice and this permission notice appear in
+// supporting documentation. No representations are made about the
+// suitability of this software for any purpose. It is provided "as is"
 // without express or implied warranty.
 
 #ifndef BOOST_MPL_VOID_HPP_INCLUDED
@@ -23,7 +23,11 @@
 namespace boost {
 namespace mpl {
 
-struct void_;
+//  [JDG Feb-4-2003] made void_ a complete type to allow it to be
+//  instantiated so that it can be passed in as an object that can be
+//  used to select an overloaded function. Possible use includes signaling
+//  a zero arity functor evaluation call.
+struct void_ {};
 
 template< typename T >
 struct is_void_