diff --git a/configure.ac b/configure.ac
index 56d0e318..77d16c8c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -151,7 +151,12 @@ AS_IF([test -d /usr/local/lib], [
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 
-AC_C_BIGENDIAN
+AC_C_BIGENDIAN(
+  AC_DEFINE(NATIVE_BIG_ENDIAN, 1, [machine is bigendian]),
+  AC_DEFINE(NATIVE_LITTLE_ENDIAN, 1, [machine is littleendian]),
+  AC_MSG_ERROR([unknown endianess]),
+  AC_MSG_WARN([universal endianess])
+)
 
 AC_MSG_CHECKING(for 128-bit arithmetic)
 have_ti_mode=no