--- db4.2-4.2.52.orig/dist/aclocal/mutex.ac
+++ db4.2-4.2.52/dist/aclocal/mutex.ac
@@ -420,7 +433,7 @@
 # x86/gcc: FreeBSD, NetBSD, BSD/OS, Linux
 if test "$db_cv_mutex" = no; then
 AC_TRY_COMPILE(,[
-#if (defined(i386) || defined(__i386__)) && defined(__GNUC__)
+#if (defined(i386) || defined(__i386__) || defined(__x86_64__)) && defined(__GNUC__)
 	exit(0);
 #else
 	FAIL TO COMPILE/LINK