diff --git a/share/xml/docbook50.dtd b/share/xml/docbook50.dtd
index 7c48939e3c..8b89b023f7 100644
--- a/share/xml/docbook50.dtd
+++ b/share/xml/docbook50.dtd
@@ -1371,7 +1371,8 @@
 
 >
 
-<!ELEMENT lineannotation (#PCDATA|inlinemediaobject|remark|superscript|subscript|xref|link|olink|anchor|biblioref|alt|annotation|indexterm|phrase|replaceable)*>
+<!ELEMENT lineannotation (#PCDATA|inlinemediaobject|remark|superscript|subscript|xref|link|olink|anchor|biblioref|alt|annotation|indexterm|phrase|replaceable|
+	trademark)*>
 
 <!ATTLIST lineannotation
 	xmlns	CDATA	#FIXED	"http://docbook.org/ns/docbook"