diff --git a/acconfig.h b/acconfig.h
index f920ea44a..cab27cabc 100644
--- a/acconfig.h
+++ b/acconfig.h
@@ -95,6 +95,9 @@
    the Guile library itself.  */
 #undef GUILE_DEBUG
 
+/* Define this to include experimental multilanguage support.  */
+#undef GUILE_LANG
+
 /* Define to implement scm_internal_select */
 #undef GUILE_ISELECT