diff --git a/reference/dom/domdocument/xinclude.xml b/reference/dom/domdocument/xinclude.xml
index 1ba18fb7c6..859b915999 100644
--- a/reference/dom/domdocument/xinclude.xml
+++ b/reference/dom/domdocument/xinclude.xml
@@ -43,7 +43,7 @@
  <refsect1 role="returnvalues">
   &reftitle.returnvalues;
   <para>
-   Returns the number of XIncludes in the document.
+   Returns the number of XIncludes in the document or -1 if some processing failed.
   </para>
  </refsect1>
  <refsect1 role="examples">