diff --git a/libbuild2-autoconf/libbuild2/autoconf/checks/BYTE_ORDER.h b/libbuild2-autoconf/libbuild2/autoconf/checks/BYTE_ORDER.h
index 35ab553..29d954c 100644
--- a/libbuild2-autoconf/libbuild2/autoconf/checks/BYTE_ORDER.h
+++ b/libbuild2-autoconf/libbuild2/autoconf/checks/BYTE_ORDER.h
@@ -43,11 +43,15 @@
 #    define BIG_ENDIAN    4321
 #    define LITTLE_ENDIAN 1234
 #    define BYTE_ORDER    LITTLE_ENDIAN
-#  elif defined(__BYTE_ORDER__) &&       \
-        defined(__ORDER_BIG_ENDIAN__) && \
-        defined(__ORDER_LITTLE_ENDIAN__)
-     /* GCC, Clang (and others, potentially).
-      */
+#  endif
+#endif
+
+/* Fallback: GCC, Clang (specifically apple-silicon and others, potentially).
+ */
+#ifndef BYTE_ORDER
+#  if defined(__BYTE_ORDER__)       && \
+      defined(__ORDER_BIG_ENDIAN__) && \
+      defined(__ORDER_LITTLE_ENDIAN__)
 #    define BYTE_ORDER    __BYTE_ORDER__
 #    define BIG_ENDIAN    __ORDER_BIG_ENDIAN__
 #    define LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__