diff --git a/include/libxml/tree.h b/include/libxml/tree.h
index e5a8fb709471f..7819d5819b427 100644
--- a/include/libxml/tree.h
+++ b/include/libxml/tree.h
@@ -454,6 +454,7 @@ struct _xmlAttr {
     xmlAttributeType atype;     /* the attribute type if validating */
     void            *psvi;	/* for type/PSVI information */
     struct _xmlID   *id;        /* the ID struct */
+    unsigned int     extra;     /* extra data for XPath/XSLT */
 };
 
 /**
@@ -592,6 +593,7 @@ struct _xmlDoc {
 				   document */
     int             properties;	/* set of xmlDocProperties for this document
 				   set at the end of parsing */
+    unsigned int    extra;      /* extra data for XPath/XSLT */
 };