diff --git a/ChangeLog b/ChangeLog
index 442995e60f..c4b889a67f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Feb  3 12:09:08 2009  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* lib/net/imap.rb (hmac_md5): should use String#ord to get ascii
+	  code from the one-character string.
+
 Tue Feb  3 11:25:41 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* load.c (load_lock): warn for circular require.  [ruby-core:20794],
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 09b5349298..d07dd42722 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -3151,8 +3151,8 @@ module Net
         k_ipad = key + "\0" * (64 - key.length)
         k_opad = key + "\0" * (64 - key.length)
         for i in 0..63
-          k_ipad[i] ^= 0x36
-          k_opad[i] ^= 0x5c
+          k_ipad[i] = (k_ipad[i].ord ^ 0x36).chr
+          k_opad[i] = (k_opad[i].ord ^ 0x5c).chr
         end
 
         digest = Digest::MD5.digest(k_ipad + text)