--- guile-1.6.4/libguile/gc_os_dep.c	2003-04-16 20:16:21.000000000 +0000
+++ guile-1.6.4-amd64/libguile/gc_os_dep.c	2003-10-20 01:52:11.543267320 +0000
@@ -205,6 +205,10 @@
 #    define I386
 #    define mach_type_known
 # endif
+# if defined(LINUX) && defined(__x86_64__)
+#    define IA64
+#    define mach_type_known
+# endif
 # if defined(LINUX) && (defined(__ia64__) || defined(__ia64))
 #    define IA64
 #    define mach_type_known