--- a/libupnpp/config.h.in
+++ b/libupnpp/config.h.in
@@ -8,6 +8,9 @@
 
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
+
+/* Define to 1 if you have the `expat' library (-lexpat). */
+#undef HAVE_LIBEXPAT
 
 /* Define to 1 if you have the `ixml' library (-lixml). */
 #undef HAVE_LIBIXML