diff --git a/ChangeLog b/ChangeLog
index d1409d1ce1..ad050137c3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
-Fri Jan  7 21:54:04 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Fri Jan  7 21:57:22 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* misc/ruby-mode.el (ruby-mode-variables), misc/ruby-style.el:
+	  show trailing whitespace.
 
 	* misc/ruby-mode.el (ruby-font-lock-syntactic-keywords): highlight
 	  regexp after open bracket.  [ruby-core:34183]
diff --git a/misc/ruby-mode.el b/misc/ruby-mode.el
index 0fec8e9cec..aaea3a0d0e 100644
--- a/misc/ruby-mode.el
+++ b/misc/ruby-mode.el
@@ -297,6 +297,7 @@ Also ignores spaces after parenthesis when 'space."
 
 (defun ruby-mode-variables ()
   (set-syntax-table ruby-mode-syntax-table)
+  (setq show-trailing-whitespace t)
   (setq local-abbrev-table ruby-mode-abbrev-table)
   (make-local-variable 'indent-line-function)
   (setq indent-line-function 'ruby-indent-line)
diff --git a/misc/ruby-style.el b/misc/ruby-style.el
index c433025dbc..3ce55cd1ab 100644
--- a/misc/ruby-style.el
+++ b/misc/ruby-style.el
@@ -54,6 +54,7 @@
    (c-basic-offset . 4)
    (tab-width . 8)
    (indent-tabs-mode . t)
+   (setq show-trailing-whitespace t)
    (c-offsets-alist
     (case-label . *)
     (label . (ruby-style-label-indent *))