--- configure.ac.orig	2008-08-28 23:51:37.000000000 -0700
+++ configure.ac	2008-08-28 23:54:56.000000000 -0700
@@ -104,7 +104,11 @@
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
-AC_C_BIGENDIAN([ENDIAN="X_BIG_ENDIAN"], [ENDIAN="X_LITTLE_ENDIAN"])
+AC_C_BIGENDIAN([ENDIAN="X_BIG_ENDIAN"], [ENDIAN="X_LITTLE_ENDIAN"],
+               [
+echo "ERROR: can't determine machine endianness"
+exit 1
+               ], [ENDIAN="X_BIG_ENDIAN"])
 
 AC_CHECK_SIZEOF([unsigned long])
 if test "$ac_cv_sizeof_unsigned_long" = 8; then