diff --git a/valid.c b/valid.c
index f285c19..9133a30 100644
--- a/valid.c
+++ b/valid.c
@@ -7,6 +7,7 @@
  * daniel@veillard.com
  */
 
+#define IN_LIBXML
 #include "libxml.h"
 
 #include <string.h>