--- Libc/Libc-391.5.21/mach/headers/thread_act.h
+++ Libc/Libc-391.2.3/mach/headers/thread_act.h
@@ -22,8 +22,6 @@
  */
 #if defined(__i386__)
 #include <mach/i386/thread_act.h>
-#elif defined(__x86_64__)
-#include <mach/x86_64/thread_act.h>
 #elif defined(__ppc__)
 #include <mach/ppc/thread_act.h>
 #elif defined(__ppc64__)