diff --git a/Yesod/Auth/Kerberos.hs b/Yesod/Auth/Kerberos.hs
--- a/Yesod/Auth/Kerberos.hs
+++ b/Yesod/Auth/Kerberos.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleContexts #-}
 -- | In-built kerberos authentication for Yesod.
 --
 -- Please note that all configuration should have been done
diff --git a/yesod-auth-kerberos.cabal b/yesod-auth-kerberos.cabal
--- a/yesod-auth-kerberos.cabal
+++ b/yesod-auth-kerberos.cabal
@@ -1,5 +1,5 @@
 name:            yesod-auth-kerberos
-version:         1.4.2
+version:         1.4.3
 license:         BSD3
 license-file:    LICENSE
 author:          Arash Rouhani
@@ -21,7 +21,7 @@
                    , bytestring              >= 0.9.1.4   && < 0.11
                    , shakespeare             >= 2.0       && < 2.1
                    , text                    >= 0.7       && < 2.0
-                   , transformers            >= 0.2.2     && < 0.4
+                   , transformers            >= 0.2.2     && < 0.5
 
     exposed-modules: Yesod.Auth.Kerberos
     ghc-options:     -Wall