diff --git a/lisp/help.el b/lisp/help.el
index b794751ecab..02e9b9e8e46 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -952,8 +952,11 @@ current buffer."
 	    (describe-function-1 defn)))))))
 
 (defun search-forward-help-for-help ()
-  "Search forward \"help window\"."
+  "Search forward in the help-for-help window.
+This command is meant to be used after issuing the `C-h C-h' command."
   (interactive)
+  (unless (get-buffer help-for-help-buffer-name)
+    (error "No %s buffer; use `C-h C-h' first" help-for-help-buffer-name))
   ;; Move cursor to the "help window".
   (pop-to-buffer help-for-help-buffer-name)
   ;; Do incremental search forward.