diff --git a/Network/HTTP/Date/Types.hs b/Network/HTTP/Date/Types.hs
--- a/Network/HTTP/Date/Types.hs
+++ b/Network/HTTP/Date/Types.hs
@@ -22,7 +22,7 @@
   , hdMinute :: !Int
   , hdSecond :: !Int
   , hdWkday  :: !Int
-  } deriving (Eq,Show)
+  } deriving (Eq,Show, Ord)
 
 {-|
   A default value for 'HTTPDate'.
diff --git a/http-date.cabal b/http-date.cabal
--- a/http-date.cabal
+++ b/http-date.cabal
@@ -1,5 +1,5 @@
 Name:                   http-date
-Version:                0.0.3
+Version:                0.0.4
 Author:                 Kazu Yamamoto <kazu@iij.ad.jp>
 Maintainer:             Kazu Yamamoto <kazu@iij.ad.jp>
 License:                BSD3