diff --git a/ChangeLog.md b/ChangeLog.md
new file mode 100644
--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,23 @@
+## 1.4.5
+
+* `envClientSessionBackend`
+
+## 1.4.4.5
+
+Support time 1.5
+
+## 1.4.4.2
+
+`neverExpires` uses dates one year in the future (instead of in 2037).
+
+## 1.4.4.1
+
+Improvements to etag/if-none-match support #868 #869
+
+## 1.4.4
+
+Add the `notModified` and `setEtag` functions.
+
+## 1.4.3
+
+Switch to mwc-random for token generation.
diff --git a/Yesod/Core.hs b/Yesod/Core.hs
--- a/Yesod/Core.hs
+++ b/Yesod/Core.hs
@@ -45,6 +45,7 @@
     , SessionBackend (..)
     , customizeSessionCookies
     , defaultClientSessionBackend
+    , envClientSessionBackend
     , clientSessionBackend
     , clientSessionDateCacher
     , loadClientSession
diff --git a/Yesod/Core/Class/Yesod.hs b/Yesod/Core/Class/Yesod.hs
--- a/Yesod/Core/Class/Yesod.hs
+++ b/Yesod/Core/Class/Yesod.hs
@@ -598,6 +598,33 @@
   (getCachedDate, _closeDateCacher) <- clientSessionDateCacher timeout
   return $ clientSessionBackend key getCachedDate
 
+-- | Create a @SessionBackend@ which reads the session key from the named
+-- environment variable.
+--
+-- This can be useful if:
+--
+-- 1. You can't rely on a persistent file system (e.g. Heroku)
+-- 2. Your application is open source (e.g. you can't commit the key)
+--
+-- By keeping a consistent value in the environment variable, your users will
+-- have consistent sessions without relying on the file system.
+--
+-- Note: A suitable value should only be obtained in one of two ways:
+--
+-- 1. Run this code without the variable set, a value will be generated and
+--    printed on @/dev/stdout/@
+-- 2. Use @clientsession-generate@
+--
+-- Since 1.4.5
+envClientSessionBackend :: Int -- ^ minutes
+                        -> String -- ^ environment variable name
+                        -> IO SessionBackend
+envClientSessionBackend minutes name = do
+    key <- CS.getKeyEnv name
+    let timeout = fromIntegral (minutes * 60)
+    (getCachedDate, _closeDateCacher) <- clientSessionDateCacher timeout
+    return $ clientSessionBackend key getCachedDate
+
 jsToHtml :: Javascript -> Html
 jsToHtml (Javascript b) = preEscapedToMarkup $ toLazyText b
 
diff --git a/Yesod/Core/Types.hs b/Yesod/Core/Types.hs
--- a/Yesod/Core/Types.hs
+++ b/Yesod/Core/Types.hs
@@ -62,6 +62,9 @@
 import Control.DeepSeq (NFData (rnf))
 import Data.Conduit.Lazy (MonadActive, monadActive)
 import Yesod.Core.TypeCache (TypeMap, KeyedTypeMap)
+#if MIN_VERSION_monad_logger(0, 3, 10)
+import Control.Monad.Logger (MonadLoggerIO (..))
+#endif
 
 -- Sessions
 type SessionMap = Map Text ByteString
@@ -436,6 +439,11 @@
     monadLoggerLog a b c d = WidgetT $ \hd ->
         liftIO $ fmap (, mempty) $ rheLog (handlerEnv hd) a b c (toLogStr d)
 
+#if MIN_VERSION_monad_logger(0, 3, 10)
+instance MonadIO m => MonadLoggerIO (WidgetT site m) where
+    askLoggerIO = WidgetT $ \hd -> return (rheLog (handlerEnv hd), mempty)
+#endif
+
 instance MonadActive m => MonadActive (WidgetT site m) where
     monadActive = lift monadActive
 instance MonadActive m => MonadActive (HandlerT site m) where
@@ -488,6 +496,11 @@
 instance MonadIO m => MonadLogger (HandlerT site m) where
     monadLoggerLog a b c d = HandlerT $ \hd ->
         liftIO $ rheLog (handlerEnv hd) a b c (toLogStr d)
+
+#if MIN_VERSION_monad_logger(0, 3, 10)
+instance MonadIO m => MonadLoggerIO (HandlerT site m) where
+    askLoggerIO = HandlerT $ \hd -> return (rheLog (handlerEnv hd))
+#endif
 
 instance Monoid (UniqueList x) where
     mempty = UniqueList id
diff --git a/changelog.md b/changelog.md
deleted file mode 100644
--- a/changelog.md
+++ /dev/null
@@ -1,19 +0,0 @@
-## 1.4.4.5
-
-Support time 1.5
-
-## 1.4.4.2
-
-`neverExpires` uses dates one year in the future (instead of in 2037).
-
-## 1.4.4.1
-
-Improvements to etag/if-none-match support #868 #869
-
-## 1.4.4
-
-Add the `notModified` and `setEtag` functions.
-
-## 1.4.3
-
-Switch to mwc-random for token generation.
diff --git a/yesod-core.cabal b/yesod-core.cabal
--- a/yesod-core.cabal
+++ b/yesod-core.cabal
@@ -1,5 +1,5 @@
 name:            yesod-core
-version:         1.4.4.5
+version:         1.4.5
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -18,7 +18,7 @@
   test/YesodCoreTest/JsLoaderSites/Bottom.hs
   test/en.msg
   test/test.hs
-  changelog.md
+  ChangeLog.md
   README.md
 
 library
@@ -34,7 +34,7 @@
                    , blaze-builder         >= 0.2.1.4  && < 0.4
                    , transformers          >= 0.2.2
                    , mtl
-                   , clientsession         >= 0.9      && < 0.10
+                   , clientsession         >= 0.9.1    && < 0.10
                    , random                >= 1.0.0.2  && < 1.2
                    , cereal                >= 0.3
                    , old-locale            >= 1.0.0.2  && < 1.1