diff --git a/share/sgml/freebsd.ent b/share/sgml/freebsd.ent
index a6eb6ccaa6..9d616661c0 100644
--- a/share/sgml/freebsd.ent
+++ b/share/sgml/freebsd.ent
@@ -15,6 +15,7 @@
   Use this entity when refering to 'UNIX' in your document.
 -->
 <!ENTITY unix "<trademark class='registered'>UNIX</trademark>">
+<!ENTITY nis "<acronym>NIS</acronym">
 
 <!-- This entity should be overridden for the print output case to
      properly render TeX. -->