diff --git a/ChangeLog b/ChangeLog
index 1a4f8bf7ea..16c16d27f7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jan 18 09:43:02 2008  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* re.c (rb_char_to_option_kcode): Regexp switch `s' should mean
+	  Windows-31J, as wells as `-Ks'.
+
 Fri Jan 18 09:22:07 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* parse.y (parser_initialize): explicitly call rb_ascii8bit_encoding().
diff --git a/re.c b/re.c
index f17e276bba..67e56cdc61 100644
--- a/re.c
+++ b/re.c
@@ -188,7 +188,7 @@ rb_char_to_option_kcode(int c, int *option, int *kcode)
 	*kcode = rb_enc_find_index("EUC-JP");
 	break;
       case 's':
-	*kcode = rb_enc_find_index("Shift_JIS");
+	*kcode = rb_enc_find_index("Windows-31J");
 	break;
       case 'u':
 	*kcode = rb_enc_find_index("UTF-8");