--- a/doc/hgrc.5.txt
+++ b/doc/hgrc.5.txt
@@ -401,9 +401,8 @@ ui::
   username;;
     The committer of a changeset created when running "commit".
     Typically a person's name and email address, e.g. "Fred Widget
-    <fred@example.com>".  Default is $EMAIL or username@hostname, unless
-    username is set to an empty string, which enforces specifying the
-    username manually.
+    <fred@example.com>".  Default is $EMAIL. If no default is found,
+    the username have to be specified manually.
   verbose;;
     Increase the amount of output printed.  True or False.  Default is False.