diff --git a/misc/ruby-additional.el b/misc/ruby-additional.el
index 7ef099b13a..b77b5260d0 100644
--- a/misc/ruby-additional.el
+++ b/misc/ruby-additional.el
@@ -106,7 +106,7 @@ Emacs to Ruby."
                      (t (when ruby-insert-encoding-magic-comment
                           (insert "# -*- coding: " coding-system " -*-\n"))))))))
 
-     (define-key ruby-mode-map "\C-c\C-u" 'ruby-encode-unicode)
+     (define-key ruby-mode-map "\C-cU" 'ruby-encode-unicode)
 
      (defun ruby-encode-unicode (beg end)
        "Convert non-ascii string in the given region to \\u{} form."