diff --git a/Web/Authenticate/OpenId.hs b/Web/Authenticate/OpenId.hs
--- a/Web/Authenticate/OpenId.hs
+++ b/Web/Authenticate/OpenId.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE DeriveDataTypeable #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE CPP #-}
 ---------------------------------------------------------
 -- |
 -- Module        : Web.Authenticate.OpenId
@@ -23,8 +24,12 @@
 import Network.HTTP.Wget
 import Text.HTML.TagSoup
 import Numeric (showHex)
-import Control.Monad.IO.Class
 import qualified Safe.Failure as A
+#if TRANSFORMERS_02
+import Control.Monad.IO.Class
+#else
+import Control.Monad.Trans
+#endif
 import Data.Generics
 import Control.Failure hiding (Error)
 import Control.Exception
diff --git a/Web/Authenticate/Rpxnow.hs b/Web/Authenticate/Rpxnow.hs
--- a/Web/Authenticate/Rpxnow.hs
+++ b/Web/Authenticate/Rpxnow.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE CPP #-}
 ---------------------------------------------------------
 --
 -- Module        : Web.Authenticate.Rpxnow
@@ -20,7 +21,11 @@
 import Text.JSON -- FIXME use Data.Object.JSON
 import Network.HTTP.Wget
 import Data.Maybe (isJust, fromJust)
+#if TRANSFORMERS_02
 import Control.Monad.IO.Class
+#else
+import Control.Monad.Trans
+#endif
 import Control.Failure
 
 -- | Information received from Rpxnow after a valid login.
diff --git a/authenticate.cabal b/authenticate.cabal
--- a/authenticate.cabal
+++ b/authenticate.cabal
@@ -1,5 +1,5 @@
 name:            authenticate
-version:         0.6.0
+version:         0.6.0.1
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
@@ -13,6 +13,9 @@
 build-type:      Simple
 homepage:        http://github.com/snoyberg/authenticate/tree/master
 
+flag transformers_02
+    description: transformers = 0.2.*
+
 library
     build-depends:   base >= 4 && < 5,
                      json >= 0.4.3 && < 0.5,
@@ -20,8 +23,12 @@
                      tagsoup >= 0.6 && < 0.9,
                      failure >= 0.0.0 && < 0.1,
                      safe-failure >= 0.4 && < 0.5,
-                     transformers >= 0.2 && < 0.3,
                      syb
+    if flag(transformers_02)
+      build-depends: transformers >= 0.2 && < 0.3
+      CPP-OPTIONS: -DTRANSFORMERS_02
+    else
+      build-depends: transformers >= 0.1 && < 0.2
     exposed-modules: Web.Authenticate.Rpxnow,
                      Web.Authenticate.OpenId
     ghc-options:     -Wall -fno-warn-orphans