diff --git a/apiary.cabal b/apiary.cabal
--- a/apiary.cabal
+++ b/apiary.cabal
@@ -1,5 +1,5 @@
 name:                apiary
-version:             0.3.0.0
+version:             0.3.1.0
 x-revision:          1
 synopsis:            Simple web framework inspired by scotty.
 description:
@@ -60,12 +60,12 @@
                      , mmorph            >=1.0 && <1.1
                      , transformers-base >=0.4 && <0.5
 
-                     , text              >=1.1 && <1.2
-                     , bytestring        >=0.10 && <0.11
-                     , blaze-builder     >=0.3 && <0.4
-                     , conduit           >=1.1 && <1.2
-                     , monad-logger      >=0.3 && <0.4
-                     , data-default      >=0.5 && <0.6
+                     , text               >=1.1 && <1.2
+                     , bytestring         >=0.10 && <0.11
+                     , blaze-builder      >=0.3 && <0.4
+                     , conduit            >=1.1 && <1.2
+                     , monad-logger       >=0.3 && <0.4
+                     , data-default-class >=0.0 && <0.1
 
                      , http-types        >=0.8 && <0.9
                      , mime-types        >=0.1 && <0.2
diff --git a/src/Control/Monad/Apiary/Action.hs b/src/Control/Monad/Apiary/Action.hs
--- a/src/Control/Monad/Apiary/Action.hs
+++ b/src/Control/Monad/Apiary/Action.hs
@@ -23,4 +23,4 @@
     ) where
 
 import Control.Monad.Apiary.Action.Internal
-import Data.Default
+import Data.Default.Class
diff --git a/src/Control/Monad/Apiary/Action/Internal.hs b/src/Control/Monad/Apiary/Action/Internal.hs
--- a/src/Control/Monad/Apiary/Action/Internal.hs
+++ b/src/Control/Monad/Apiary/Action/Internal.hs
@@ -20,7 +20,7 @@
 import Control.Monad.Trans.Control
 import Network.Wai
 import Network.Mime
-import Data.Default
+import Data.Default.Class
 import Data.Monoid
 import Network.HTTP.Types
 import Blaze.ByteString.Builder
@@ -164,8 +164,8 @@
 modifyHeader :: Monad m => (ResponseHeaders -> ResponseHeaders) -> ActionT m ()
 modifyHeader f = modifyState (\s -> s {actionHeaders = f $ actionHeaders s } )
 
-addHeader :: Monad m => Header -> ActionT m ()
-addHeader h = modifyHeader (h:)
+addHeader :: Monad m => HeaderName -> S.ByteString -> ActionT m ()
+addHeader h v = modifyHeader ((h,v):)
 
 setHeaders :: Monad m => ResponseHeaders -> ActionT m ()
 setHeaders hs = modifyHeader (const hs)