diff --git a/doc/whatis.texi b/doc/whatis.texi
index 4e9dfd1bb..97d4da2aa 100644
--- a/doc/whatis.texi
+++ b/doc/whatis.texi
@@ -38,6 +38,12 @@ services can authenticate each other.
 @global@let@sub=@xsub
 @end tex
 
+@ifhtml
+@macro sub{arg}
+<\arg\>
+@end macro
+@end ifhtml
+
 @quotation
 @strong{Note:} This discussion is about Kerberos version 4, but version
 5 works similarly.