diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,6 +1,10 @@
+## 1.6.0
+
+* Upgrade to yesod-core 1.6.0
+
 ## 1.5.9.1
 
-* Fix broken Haddocks
+* Fixes a Haddock syntax error in 1.5.9 [#1473](https://github.com/yesodweb/yesod/pull/1473)
 
 ## 1.5.9
 * Add byLabelExact and related functions
diff --git a/Yesod/Test.hs b/Yesod/Test.hs
--- a/Yesod/Test.hs
+++ b/Yesod/Test.hs
@@ -6,6 +6,7 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE ImplicitParams #-}
 {-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 
 {-|
 Yesod.Test is a pragmatic framework for testing web applications built
@@ -63,6 +64,7 @@
     , addFile
     , setRequestBody
     , RequestBuilder
+    , SIO
     , setUrl
     , clickOn
 
@@ -135,7 +137,8 @@
 import Data.CaseInsensitive (CI)
 import Network.Wai
 import Network.Wai.Test hiding (assertHeader, assertNoHeader, request)
-import qualified Control.Monad.Trans.State as ST
+import Control.Monad.Trans.Reader (ReaderT (..))
+import Conduit (MonadThrow)
 import Control.Monad.IO.Class
 import System.IO
 import Yesod.Core.Unsafe (runFakeHandler)
@@ -147,6 +150,7 @@
 import qualified Text.XML.Cursor as C
 import qualified Text.HTML.DOM as HD
 import Control.Monad.Trans.Writer
+import Data.IORef
 import qualified Data.Map as M
 import qualified Web.Cookie as Cookie
 import qualified Blaze.ByteString.Builder as Builder
@@ -180,7 +184,7 @@
 -- | A single test case, to be run with 'yit'.
 --
 -- Since 1.2.0
-type YesodExample site = ST.StateT (YesodExampleData site) IO
+type YesodExample site = SIO (YesodExampleData site)
 
 -- | Mapping from cookie name to value.
 --
@@ -203,13 +207,13 @@
 --
 -- Since 1.2.0
 getTestYesod :: YesodExample site site
-getTestYesod = fmap yedSite ST.get
+getTestYesod = fmap yedSite getSIO
 
 -- | Get the most recently provided response value, if available.
 --
 -- Since 1.2.0
 getResponse :: YesodExample site (Maybe SResponse)
-getResponse = fmap yedResponse ST.get
+getResponse = fmap yedResponse getSIO
 
 data RequestBuilderData site = RequestBuilderData
     { rbdPostData :: RBDPostData
@@ -232,7 +236,7 @@
 -- | The 'RequestBuilder' state monad constructs a URL encoded string of arguments
 -- to send with your requests. Some of the functions that run on it use the current
 -- response to analyze the forms that the server is expecting to receive.
-type RequestBuilder site = ST.StateT (RequestBuilderData site) IO
+type RequestBuilder site = SIO (RequestBuilderData site)
 
 -- | Start describing a Tests suite keeping cookies and a reference to the tested 'Application'
 -- and 'ConnectionPool'
@@ -249,7 +253,7 @@
     unYesod (YesodSpecGroup x y) = Hspec.specGroup x $ map unYesod y
     unYesod (YesodSpecItem x y) = Hspec.specItem x $ do
         app <- toWaiAppPlain site
-        ST.evalStateT y YesodExampleData
+        evalSIO y YesodExampleData
             { yedApp = app
             , yedSite = site
             , yedCookies = M.empty
@@ -269,7 +273,7 @@
       unYesod getSiteAction' (YesodSpecItem x y) = Hspec.specItem x $ do
         site <- getSiteAction'
         app <- toWaiAppPlain site
-        ST.evalStateT y YesodExampleData
+        evalSIO y YesodExampleData
             { yedApp = app
             , yedSite = site
             , yedCookies = M.empty
@@ -290,7 +294,7 @@
     unYesod (YesodSpecGroup x y) = Hspec.specGroup x $ map unYesod y
     unYesod (YesodSpecItem x y) = Hspec.specItem x $ do
         app <- getApp
-        ST.evalStateT y YesodExampleData
+        evalSIO y YesodExampleData
             { yedApp = app
             , yedSite = site
             , yedCookies = M.empty
@@ -303,12 +307,11 @@
 
 -- Performs a given action using the last response. Use this to create
 -- response-level assertions
-withResponse' :: MonadIO m
-              => (state -> Maybe SResponse)
+withResponse' :: (state -> Maybe SResponse)
               -> [T.Text]
-              -> (SResponse -> ST.StateT state m a)
-              -> ST.StateT state m a
-withResponse' getter errTrace f = maybe err f . getter =<< ST.get
+              -> (SResponse -> SIO state a)
+              -> SIO state a
+withResponse' getter errTrace f = maybe err f . getter =<< getSIO
  where err = failure msg
        msg = if null errTrace
              then "There was no response, you should make a request."
@@ -327,11 +330,10 @@
 parseHTML html = fromDocument $ HD.parseLBS html
 
 -- | Query the last response using CSS selectors, returns a list of matched fragments
-htmlQuery' :: MonadIO m
-           => (state -> Maybe SResponse)
+htmlQuery' :: (state -> Maybe SResponse)
            -> [T.Text]
            -> Query
-           -> ST.StateT state m [HtmlLBS]
+           -> SIO state [HtmlLBS]
 htmlQuery' getter errTrace query = withResponse' getter ("Tried to invoke htmlQuery' in order to read HTML of a previous response." : errTrace) $ \ res ->
   case findBySelector (simpleBody res) query of
     Left err -> failure $ query <> " did not parse: " <> T.pack (show err)
@@ -496,14 +498,14 @@
 -- | Add a parameter with the given name and value to the request body.
 addPostParam :: T.Text -> T.Text -> RequestBuilder site ()
 addPostParam name value =
-  ST.modify $ \rbd -> rbd { rbdPostData = (addPostData (rbdPostData rbd)) }
+  modifySIO $ \rbd -> rbd { rbdPostData = (addPostData (rbdPostData rbd)) }
   where addPostData (BinaryPostData _) = error "Trying to add post param to binary content."
         addPostData (MultipleItemsPostData posts) =
           MultipleItemsPostData $ ReqKvPart name value : posts
 
 -- | Add a parameter with the given name and value to the query string.
 addGetParam :: T.Text -> T.Text -> RequestBuilder site ()
-addGetParam name value = ST.modify $ \rbd -> rbd
+addGetParam name value = modifySIO $ \rbd -> rbd
     { rbdGets = (TE.encodeUtf8 name, Just $ TE.encodeUtf8 value)
               : rbdGets rbd
     }
@@ -522,7 +524,7 @@
         -> RequestBuilder site ()
 addFile name path mimetype = do
   contents <- liftIO $ BSL8.readFile path
-  ST.modify $ \rbd -> rbd { rbdPostData = (addPostData (rbdPostData rbd) contents) }
+  modifySIO $ \rbd -> rbd { rbdPostData = (addPostData (rbdPostData rbd) contents) }
     where addPostData (BinaryPostData _) _ = error "Trying to add file after setting binary content."
           addPostData (MultipleItemsPostData posts) contents =
             MultipleItemsPostData $ ReqFilePart name path contents mimetype : posts
@@ -531,7 +533,7 @@
 -- This looks up the name of a field based on the contents of the label pointing to it.
 genericNameFromLabel :: (T.Text -> T.Text -> Bool) -> T.Text -> RequestBuilder site T.Text
 genericNameFromLabel match label = do
-  mres <- fmap rbdResponse ST.get
+  mres <- fmap rbdResponse getSIO
   res <-
     case mres of
       Nothing -> failure "genericNameFromLabel: No response available"
@@ -798,7 +800,7 @@
 -- Since 1.4.3.2
 getRequestCookies :: RequestBuilder site Cookies
 getRequestCookies = do
-  requestBuilderData <- ST.get
+  requestBuilderData <- getSIO
   headers <- case simpleHeaders Control.Applicative.<$> rbdResponse requestBuilderData of
                   Just h -> return h
                   Nothing -> failure "getRequestCookies: No request has been made yet; the cookies can't be looked up."
@@ -906,7 +908,7 @@
 -- > request $ do
 -- >   setMethod methodPut
 setMethod :: H.Method -> RequestBuilder site ()
-setMethod m = ST.modify $ \rbd -> rbd { rbdMethod = m }
+setMethod m = modifySIO $ \rbd -> rbd { rbdMethod = m }
 
 -- | Sets the URL used by the request.
 --
@@ -921,7 +923,7 @@
        => url
        -> RequestBuilder site ()
 setUrl url' = do
-    site <- fmap rbdSite ST.get
+    site <- fmap rbdSite getSIO
     eurl <- Yesod.Core.Unsafe.runFakeHandler
         M.empty
         (const $ error "Yesod.Test: No logger available")
@@ -929,7 +931,7 @@
         (toTextUrl url')
     url <- either (error . show) return eurl
     let (urlPath, urlQuery) = T.break (== '?') url
-    ST.modify $ \rbd -> rbd
+    modifySIO $ \rbd -> rbd
         { rbdPath =
             case DL.filter (/="") $ H.decodePathSegments $ TE.encodeUtf8 urlPath of
                 ("http:":_:rest) -> rest
@@ -968,7 +970,7 @@
 -- > request $ do
 -- >   setRequestBody $ encode $ object ["age" .= (1 :: Integer)]
 setRequestBody :: BSL8.ByteString -> RequestBuilder site ()
-setRequestBody body = ST.modify $ \rbd -> rbd { rbdPostData = BinaryPostData body }
+setRequestBody body = modifySIO $ \rbd -> rbd { rbdPostData = BinaryPostData body }
 
 -- | Adds the given header to the request; see "Network.HTTP.Types.Header" for creating 'Header's.
 --
@@ -978,7 +980,7 @@
 -- > request $ do
 -- >   addRequestHeader (hUserAgent, "Chrome/41.0.2228.0")
 addRequestHeader :: H.Header -> RequestBuilder site ()
-addRequestHeader header = ST.modify $ \rbd -> rbd
+addRequestHeader header = modifySIO $ \rbd -> rbd
     { rbdHeaders = header : rbdHeaders rbd
     }
 
@@ -998,9 +1000,9 @@
 request :: RequestBuilder site ()
         -> YesodExample site ()
 request reqBuilder = do
-    YesodExampleData app site oldCookies mRes <- ST.get
+    YesodExampleData app site oldCookies mRes <- getSIO
 
-    RequestBuilderData {..} <- liftIO $ ST.execStateT reqBuilder RequestBuilderData
+    RequestBuilderData {..} <- liftIO $ execSIO reqBuilder RequestBuilderData
       { rbdPostData = MultipleItemsPostData []
       , rbdResponse = mRes
       , rbdMethod = "GET"
@@ -1040,7 +1042,7 @@
         }) app
     let newCookies = parseSetCookies $ simpleHeaders response
         cookies' = M.fromList [(Cookie.setCookieName c, c) | c <- newCookies] `M.union` cookies
-    ST.put $ YesodExampleData app site cookies' (Just response)
+    putSIO $ YesodExampleData app site cookies' (Just response)
   where
     isFile (ReqFilePart _ _ _ _) = True
     isFile _ = False
@@ -1144,14 +1146,14 @@
 testApp site middleware = (site, middleware)
 type YSpec site = Hspec.SpecWith (TestApp site)
 
-instance YesodDispatch site => Hspec.Example (ST.StateT (YesodExampleData site) IO a) where
-    type Arg (ST.StateT (YesodExampleData site) IO a) = TestApp site
+instance YesodDispatch site => Hspec.Example (SIO (YesodExampleData site) a) where
+    type Arg (SIO (YesodExampleData site) a) = TestApp site
 
     evaluateExample example params action =
         Hspec.evaluateExample
             (action $ \(site, middleware) -> do
                 app <- toWaiAppPlain site
-                _ <- ST.evalStateT example YesodExampleData
+                _ <- evalSIO example YesodExampleData
                     { yedApp = middleware app
                     , yedSite = site
                     , yedCookies = M.empty
@@ -1160,3 +1162,27 @@
                 return ())
             params
             ($ ())
+
+-- | State + IO
+--
+-- @since 1.6.0
+newtype SIO s a = SIO (ReaderT (IORef s) IO a)
+  deriving (Functor, Applicative, Monad, MonadIO, MonadThrow, MonadUnliftIO)
+
+getSIO :: SIO s s
+getSIO = SIO $ ReaderT readIORef
+
+putSIO :: s -> SIO s ()
+putSIO s = SIO $ ReaderT $ \ref -> writeIORef ref $! s
+
+modifySIO :: (s -> s) -> SIO s ()
+modifySIO f = SIO $ ReaderT $ \ref -> modifyIORef' ref f
+
+evalSIO :: SIO s a -> s -> IO a
+evalSIO (SIO (ReaderT f)) s = newIORef s >>= f
+
+execSIO :: SIO s () -> s -> IO s
+execSIO (SIO (ReaderT f)) s = do
+  ref <- newIORef s
+  f ref
+  readIORef ref
diff --git a/test/main.hs b/test/main.hs
--- a/test/main.hs
+++ b/test/main.hs
@@ -1,3 +1,6 @@
+-- Ignore warnings about using deprecated byLabel/fileByLabel functions
+{-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}
+
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE CPP #-}
@@ -34,7 +37,7 @@
 import qualified Data.Map as Map
 import qualified Text.HTML.DOM as HD
 import Network.HTTP.Types.Status (status301, status303, unsupportedMediaType415)
-import Control.Exception.Lifted(SomeException, try)
+import UnliftIO.Exception (tryAny, SomeException, try)
 
 parseQuery_ :: Text -> [[SelectorGroup]]
 parseQuery_ = either error id . parseQuery
@@ -189,7 +192,7 @@
               bodyEquals "<html><head><title>Hello</title></head><body><p>Hello World</p><p>Hello Moon</p></body></html>"
 
               get ("/htmlWithLink" :: Text)
-              (bad :: Either SomeException ()) <- try (clickOn "a#nonexistentlink")
+              bad <- tryAny (clickOn "a#nonexistentlink")
               assertEq "bad link" (isLeft bad) True
 
 
diff --git a/yesod-test.cabal b/yesod-test.cabal
--- a/yesod-test.cabal
+++ b/yesod-test.cabal
@@ -1,5 +1,5 @@
 name:               yesod-test
-version:            1.5.9.1
+version:            1.6.0
 license:            MIT
 license-file:       LICENSE
 author:             Nubis <nubis@woobiz.com.ar>
@@ -27,7 +27,6 @@
                    , hspec-core                == 2.*
                    , html-conduit              >= 0.1
                    , http-types                >= 0.7
-                   , monad-control
                    , network                   >= 2.2
                    , persistent                >= 1.0
                    , pretty-show               >= 1.6
@@ -38,7 +37,8 @@
                    , wai-extra
                    , xml-conduit               >= 1.0
                    , xml-types                 >= 0.3
-                   , yesod-core                >= 1.4.14
+                   , yesod-core                >= 1.6
+                   , conduit
 
     exposed-modules: Yesod.Test
                      Yesod.Test.CssQuery
@@ -58,11 +58,11 @@
                           , containers
                           , html-conduit
                           , yesod-core
-                          , yesod-form >= 1.4.14
+                          , yesod-form >= 1.6
                           , text
                           , wai
-                          , lifted-base
                           , http-types
+                          , unliftio
 
 source-repository head
   type: git