Index: simgear/nasal/cppbind/NasalHash.hxx
--- simgear/nasal/cppbind/NasalHash.hxx.orig
+++ simgear/nasal/cppbind/NasalHash.hxx
@@ -24,6 +24,8 @@
 
 #include <simgear/structure/map.hxx>
 #include <boost/iterator/iterator_facade.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/is_convertible.hpp>
 
 namespace nasal
 {
