diff --git a/yesod-core/Yesod/Core.hs b/yesod-core/Yesod/Core.hs
index 4362cee1..27f9c8be 100644
--- a/yesod-core/Yesod/Core.hs
+++ b/yesod-core/Yesod/Core.hs
@@ -33,6 +33,8 @@ module Yesod.Core
     , clientSessionBackend
     , saveClientSession
     , loadClientSession
+    , Header(..)
+    , BackendSession
     -- * JS loaders
     , loadJsYepnope
     , ScriptLoadPosition (..)
@@ -50,6 +52,7 @@ module Yesod.Core
     ) where
 
 import Yesod.Internal.Core
+import Yesod.Internal (Header(..))
 import Yesod.Content
 import Yesod.Dispatch
 import Yesod.Handler
diff --git a/yesod-core/Yesod/Internal/Core.hs b/yesod-core/Yesod/Internal/Core.hs
index 0726cca2..6482e137 100644
--- a/yesod-core/Yesod/Internal/Core.hs
+++ b/yesod-core/Yesod/Internal/Core.hs
@@ -31,6 +31,7 @@ module Yesod.Internal.Core
     , clientSessionBackend
     , saveClientSession
     , loadClientSession
+    , BackendSession
       -- * jsLoader
     , ScriptLoadPosition (..)
     , BottomOfHeadAsync
@@ -323,20 +324,6 @@ $doctype 5
         key <- CS.getKey CS.defaultKeyFile
         return $ Just $ clientSessionBackend key 120
 
-type Session = [(Text, S8.ByteString)]
-
-data SessionBackend master = SessionBackend
-    { sbSaveSession :: master
-                    -> W.Request
-                    -> UTCTime -- ^ The current time
-                    -> Session -- ^ The old session (before running handler)
-                    -> Session -- ^ The final session
-                    -> IO [Header]
-    , sbLoadSession :: master
-                    -> W.Request
-                    -> UTCTime -- ^ The current time
-                    -> IO Session
-    }
 
 messageLoggerHandler :: Yesod m
                      => Loc -> LogLevel -> Text -> GHandler s m ()
@@ -724,7 +711,7 @@ loadClientSession :: Yesod master
                   -> master
                   -> W.Request
                   -> UTCTime
-                  -> IO Session
+                  -> IO BackendSession
 loadClientSession key _ req now = return . fromMaybe [] $ do
     raw <- lookup "Cookie" $ W.requestHeaders req
     val <- lookup sessionName $ parseCookies raw
@@ -737,12 +724,12 @@ saveClientSession :: Yesod master
                   -> master
                   -> W.Request
                   -> UTCTime
-                  -> Session
-                  -> Session
+                  -> BackendSession
+                  -> BackendSession
                   -> IO [Header]
 saveClientSession key timeout master _ now _ sess = do
     -- fixme should we be caching this?
-    iv <- liftIO $ CS.randomIV
+    iv <- liftIO CS.randomIV
     return [AddCookie def
         { setCookieName = sessionName
         , setCookieValue = sessionVal iv
diff --git a/yesod-core/Yesod/Internal/Session.hs b/yesod-core/Yesod/Internal/Session.hs
index 320f7b86..ac84a862 100644
--- a/yesod-core/Yesod/Internal/Session.hs
+++ b/yesod-core/Yesod/Internal/Session.hs
@@ -1,8 +1,11 @@
 module Yesod.Internal.Session
     ( encodeClientSession
     , decodeClientSession
+    , BackendSession
+    , SessionBackend(..)
     ) where
 
+import Yesod.Internal (Header(..))
 import qualified Web.ClientSession as CS
 import Data.Serialize
 import Data.Time
@@ -12,6 +15,24 @@ import Data.Text (Text, pack, unpack)
 import Control.Arrow (first)
 import Control.Applicative ((<$>))
 
+import qualified Data.ByteString.Char8 as S8
+import qualified Network.Wai as W
+
+type BackendSession = [(Text, S8.ByteString)]
+
+data SessionBackend master = SessionBackend
+    { sbSaveSession :: master
+                    -> W.Request
+                    -> UTCTime -- ^ The current time
+                    -> BackendSession -- ^ The old session (before running handler)
+                    -> BackendSession -- ^ The final session
+                    -> IO [Header]
+    , sbLoadSession :: master
+                    -> W.Request
+                    -> UTCTime -- ^ The current time
+                    -> IO BackendSession
+    }
+
 encodeClientSession :: CS.Key
                     -> CS.IV
                     -> UTCTime -- ^ expire time
diff --git a/yesod-core/test/YesodCoreTest/WaiSubsite.hs b/yesod-core/test/YesodCoreTest/WaiSubsite.hs
index baf66979..ee313c32 100644
--- a/yesod-core/test/YesodCoreTest/WaiSubsite.hs
+++ b/yesod-core/test/YesodCoreTest/WaiSubsite.hs
@@ -4,7 +4,6 @@ module YesodCoreTest.WaiSubsite (specs, Widget) where
 import YesodCoreTest.YesodTest
 import Yesod.Core
 import qualified Network.HTTP.Types as H
-import Network.Wai
 
 myApp :: Application
 myApp _ = return $ responseLBS H.status200 [("Content-type", "text/plain")] "WAI"