diff --git i/src/test-subclassing.c w/src/test-subclassing.c
index dd099e4..0758164 100644
--- i/src/test-subclassing.c
+++ w/src/test-subclassing.c
@@ -1,4 +1,5 @@
 #include <libxml/tree.h>
+#include <libxml/parser.h>
 #include <stdio.h>
 #include <string.h>