diff -ru libmikmod-3.1.11-old/include/mikmod.h.in libmikmod-3.1.11/include/mikmod.h.in
--- libmikmod-3.1.11-old/include/mikmod.h.in	2004-05-21 13:26:08.824106896 -0500
+++ libmikmod-3.1.11/include/mikmod.h.in	2004-05-21 13:26:39.024515736 -0500
@@ -85,7 +85,7 @@
 
 @DOES_NOT_HAVE_SIGNED@
 
-#if defined(__arch64__) || defined(__alpha)
+#if defined(__arch64__) || defined(__alpha) || defined(__x86_64)
 /* 64 bit architectures */
 
 typedef signed char     SBYTE;      /* 1 byte, signed */