diff --git a/ChangeLog b/ChangeLog
index 753aea4d54..02c198ee6d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Thu Jul 31 12:23:53 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* pack.c (pack_unpack): upper half of hexdigits has never been used.
+
 Thu Jul 31 11:31:29 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/syck/syck.h (ASSERT): fix typo at r18176.
diff --git a/pack.c b/pack.c
index f7f51ac9fa..8f26365d7c 100644
--- a/pack.c
+++ b/pack.c
@@ -1291,7 +1291,7 @@ infected_str_new(const char *ptr, long len, VALUE str)
 static VALUE
 pack_unpack(VALUE str, VALUE fmt)
 {
-    static const char *hexdigits = "0123456789abcdef0123456789ABCDEFx";
+    static const char hexdigits[] = "0123456789abcdef";
     char *s, *send;
     char *p, *pend;
     VALUE ary;