(describe-function): Don't pass `nil' as default.

diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 14ceacfd92fd4404bb51c17da322abd9af408738..32719275eddfea89b7f10e131de770da9b1a50f9 100644 (file)
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -113,7 +113,8 @@ With ARG, you are asked to choose which language."
      (setq val (completing-read (if fn
                                    (format "Describe function (default %s): " fn)
                                  "Describe function: ")
-                               obarray 'fboundp t nil nil (symbol-name fn)))
+                               obarray 'fboundp t nil nil
+                               (and fn (symbol-name fn))))
      (list (if (equal val "")
               fn (intern val)))))
   (if (null function)