diff --git a/Web/Cookie.hs b/Web/Cookie.hs
--- a/Web/Cookie.hs
+++ b/Web/Cookie.hs
@@ -47,6 +47,7 @@
 import Control.Arrow ((***))
 import Data.Maybe (isJust)
 import Data.Default (Default (def))
+import Control.DeepSeq (NFData (rnf))
 
 -- | Textual cookies. Functions assume UTF8 encoding.
 type CookiesText = [(Text, Text)]
@@ -104,6 +105,17 @@
     , setCookieSecure :: Bool
     }
     deriving (Eq, Show)
+
+instance NFData SetCookie where
+    rnf (SetCookie a b c d e f g h) =
+        rnf a `seq`
+        rnf b `seq`
+        rnf c `seq`
+        rnf d `seq`
+        rnf e `seq`
+        rnf f `seq`
+        rnf g `seq`
+        rnf h
 
 instance Default SetCookie where
     def = SetCookie
diff --git a/cookie.cabal b/cookie.cabal
--- a/cookie.cabal
+++ b/cookie.cabal
@@ -1,5 +1,5 @@
 name:            cookie
-version:         0.4.0.1
+version:         0.4.1
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -19,6 +19,7 @@
                    , time                      >= 1.1.4
                    , text                      >= 0.7
                    , data-default
+                   , deepseq
     exposed-modules: Web.Cookie
     ghc-options:     -Wall