diff --git a/ABI.h.in b/ABI.h.in
index 21c9139c0a..6300ada4e4 100644
--- a/ABI.h.in
+++ b/ABI.h.in
@@ -432,6 +432,12 @@ suppression macro @KWIML@_ABI_NO_VERIFY was defined.
 #  define @KWIML@_ABI_ENDIAN_ID @KWIML@_ABI_ENDIAN_ID_BIG
 # endif
 
+/* Xtensa */
+#elif defined(__XTENSA_EB__)
+# define @KWIML@_ABI_ENDIAN_ID @KWIML@_ABI_ENDIAN_ID_BIG
+#elif defined(__XTENSA_EL__)
+# define @KWIML@_ABI_ENDIAN_ID @KWIML@_ABI_ENDIAN_ID_LITTLE
+
 /* Unknown CPU */
 #elif !defined(@KWIML@_ABI_NO_ERROR_ENDIAN)
 # error "Byte order of target CPU unknown."