diff --git a/ChangeLog b/ChangeLog
index 5971645238..35af5ee6bc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sat Dec 22 17:45:11 2007  NARUSE, Yui <naruse@ruby-lang.org>
+
+	* ext/nkf/nkf.c (Init_nkf): use rb_ascii_encoding() for
+	  rb_nkf_enc_get("US-ASCII").
+	  * if use rb_nkf_enc_get("US-ASCII"), ruby will crash - this is bug?
+
 Sat Dec 22 17:39:03 2007  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* lib/mkmf.rb ($extmk): fixed broken condition.
diff --git a/ext/nkf/nkf.c b/ext/nkf/nkf.c
index 4f340f0b92..68f8e3f6b6 100644
--- a/ext/nkf/nkf.c
+++ b/ext/nkf/nkf.c
@@ -485,7 +485,7 @@ Init_nkf()
     rb_define_const(mNKF, "NOCONV",	Qnil);
     rb_define_const(mNKF, "UNKNOWN",	Qnil);
     rb_define_const(mNKF, "BINARY",	rb_enc_from_encoding(rb_nkf_enc_get("BINARY")));
-    rb_define_const(mNKF, "ASCII",	rb_enc_from_encoding(rb_nkf_enc_get("US-ASCII")));
+    rb_define_const(mNKF, "ASCII",	rb_enc_from_encoding(rb_ascii_encoding()));
     rb_define_const(mNKF, "JIS",	rb_enc_from_encoding(rb_nkf_enc_get("ISO-2022-JP")));
     rb_define_const(mNKF, "EUC",	rb_enc_from_encoding(rb_nkf_enc_get("EUC-JP")));
     rb_define_const(mNKF, "SJIS",	rb_enc_from_encoding(rb_nkf_enc_get("Shift_JIS")));