diff --git a/man/maintaining.texi b/man/maintaining.texi
index cff12dfb026..facde7020bc 100644
--- a/man/maintaining.texi
+++ b/man/maintaining.texi
@@ -182,7 +182,8 @@ convenient.  Each name recorded is called a @dfn{tag}.
 @item
 In C code, any C function or typedef is a tag, and so are definitions of
 @code{struct}, @code{union} and @code{enum}.
-@code{#define} macro definitions and @code{enum} constants are also
+@code{#define} macro definitions, @code{#undef} and @code{enum}
+constants are also 
 tags, unless you specify @samp{--no-defines} when making the tags table.
 Similarly, global variables are tags, unless you specify
 @samp{--no-globals}.  Use of @samp{--no-globals} and @samp{--no-defines}