1 files changed, 5 insertions, 2 deletions

diff --git a/src/editfns.c b/src/editfns.c
index 6599f23bae2..0812fb9b87e 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -732,10 +732,13 @@ DEFUN ("user-real-uid", Fuser_real_uid, Suser_real_uid, 0, 0, 0,
 
 DEFUN ("user-full-name", Fuser_full_name, Suser_full_name, 0, 1, 0,
   "Return the full name of the user logged in, as a string.\n\
+If the full name corresponding to Emacs's userid is not known,\n\
+return \"unknown\".\n\
+\n\
 If optional argument UID is an integer, return the full name of the user\n\
-with that uid, or \"unknown\" if there is no such user.\n\
+with that uid, or nil if there is no such user.\n\
 If UID is a string, return the full name of the user with that login\n\
-name, or \"unknown\" if no such user could be found.")
+name, or nil if there is no such user.")
   (uid)
      Lisp_Object uid;
 {