diff --git a/simgear/nasal/naref.h b/simgear/nasal/naref.h
index f1919a2b..beedeced 100644
--- a/simgear/nasal/naref.h
+++ b/simgear/nasal/naref.h
@@ -11,7 +11,8 @@
  * tested */
 # define NASAL_NAN64
 #elif defined(_M_IX86) || defined(i386) || defined(__x86_64) || \
-      defined(__ia64__) || defined(_M_IA64) || defined(__ARMEL__) 
+      defined(__ia64__) || defined(_M_IA64) || defined(__ARMEL__) || \
+      defined(_M_X64) 
 # define NASAL_LE
 #elif defined(__sparc) || defined(__ppc__) || defined(__PPC) || \
       defined(__mips) || defined(__ARMEB__)