--- configure.ac.orig	2026-09-02 15:44:14.000000000 +0000
+++ configure.ac	2026-09-04 14:48:41.166531000 +0000
@@ -57,6 +57,7 @@
 AC_SUBST(XO_PATH)
 AC_SUBST(CFLAGS_W)
 AC_CONFIG_FILES([Makefile])
+AC_CONFIG_SUBDIRS([xo])
 AC_OUTPUT
 
 dnl -- Prevent accidental edits.