diff --git a/emacs.el b/emacs.el
index 74812ac..0f25780 100644
--- a/emacs.el
+++ b/emacs.el
@@ -1,6 +1,6 @@
 ;;; emacs.el --- 10sr emacs initialization
 
-;; Time-stamp: <2018-10-16 18:11:49 JST 10sr>
+;; Time-stamp: <2018-10-16 18:13:02 JST 10sr>
 
 ;;; Code:
 
@@ -2721,6 +2721,11 @@ If current path was not found in the parent revision try to go up path."
 ;; (git-walktree--parent-sha1 "HEAD")
 ;; (git-walktree--parent-sha1 "ae4b80f")
 
+(defun git-revision-known-child-revision ()
+  "Open known revision of current path."
+  (interactive)
+  nil)
+
 (defvar git-walktree-mode-map
   (let ((map (make-sparse-keymap)))
     (define-key map "n" 'git-walktree-mode-next-line)