diff --git a/TODO b/TODO
index 32cea5e..13175ec 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,8 @@
+        Non-native version can't be built
+
+                may need to dig into ancient svn history to find old
+                makefiles that used to build it
+
         Mac OS X fixes:
 
                 figure out why i486-cleanup.pl basically eats all
diff --git a/configure.ac b/configure.ac
index 94bf2f1..327efd1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -67,11 +67,11 @@ AC_SUBST(HOST_NATIVE)
 AC_ARG_ENABLE([native],
 	      AC_HELP_STRING([--enable-native],
 			     [native or nonnative (default is native)]),
-	      [var_native=$enable_native], [var_native=no] )
+	      [var_native=$enable_native], [var_native=yes] )
 if test "$var_native" = "yes"; then
-  NO_NATIVE=TRUE
-else
   NO_NATIVE=FALSE
+else
+  NO_NATIVE=TRUE
 fi
 AC_SUBST(NO_NATIVE)
 
diff --git a/include/syn68k_public.h b/include/syn68k_public.h
index 8aaf02f..908e052 100644
--- a/include/syn68k_public.h
+++ b/include/syn68k_public.h
@@ -12,7 +12,8 @@
 # if defined(__BIG_ENDIAN__) || defined(m68k) || defined(mc68000) \
      || defined(sparc) || defined(powerpc) || defined (__ppc__)
 #  define BIGENDIAN  /* ARDI naming convention, why rock the boat? */
-# elif defined(__alpha) || defined(i860) || defined(vax) || defined(i386)
+# elif defined(__alpha) || defined(i860) || defined(vax) || defined(i386) \
+     || defined(__x86_64)
 #  define LITTLEENDIAN
 # else
 #  error "Unknown CPU type"
@@ -35,7 +36,7 @@
 #  define QUADALIGN
 # elif !defined(m68k) && !defined(mc68000) && !defined(i386) \
        && !defined(vax) && !defined(__alpha) && !defined(powerpc) \
-       && !defined (__ppc__)
+       && !defined (__ppc__) && !defined(__x86_64)
 #  error Unknown CPU type
 # endif
 #endif
diff --git a/runtime/syn68k_header.c b/runtime/syn68k_header.c
index 85d830b..d680ee6 100644
--- a/runtime/syn68k_header.c
+++ b/runtime/syn68k_header.c
@@ -17,6 +17,8 @@
 # define GLOBAL_REGISTER_DECLS register const uint16 *code asm ("$9");
 #elif defined (powerpc) || defined (__ppc__)
 # define GLOBAL_REGISTER_DECLS register const uint16 *code asm ("%r13");
+#elif defined(__x86_64)
+# define GLOBAL_REGISTER_DECLS register const uint16 *code asm ("%rsi");
 #else
 # error "Choose a global register to hold the current synthetic PC.  Make sure it is saved by the normal calling convention."
 #endif