diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,10 @@
+Version 0.2.2: November 2, 2010
+
+  * update mtl dependency to 2.0.  Note that due to the changed
+    definition of Cont, this version does NOT compile with versions of
+    mtl previous to 2.0.  If you need to use a version of mtl < 2.0
+    then stick with 0.2.1.3 for now.
+
 Version 0.2.1.3: May 30, 2010
 
   * update cairo version range to allow 0.11
diff --git a/Graphics/Rendering/Diagrams/Layouts.hs b/Graphics/Rendering/Diagrams/Layouts.hs
--- a/Graphics/Rendering/Diagrams/Layouts.hs
+++ b/Graphics/Rendering/Diagrams/Layouts.hs
@@ -58,6 +58,7 @@
 import Graphics.Rendering.Diagrams.Engine (sizeAndPos)
 import Control.Arrow (first)
 import Control.Monad.Cont
+import Control.Monad.Identity
 
 import Data.List (transpose)
 import Data.Tree
@@ -409,10 +410,6 @@
 
 -- Miscellaneous ---------------------------------
 
-newtype Identity a = Identity a
-instance Functor Identity where
-  fmap f (Identity x) = Identity (f x)
-
 data Padded = Padded Double Double HAlignment VAlignment
 instance LayoutClass Padded Identity where
   layoutSizeAndPos (Padded dw dh ha va) (Identity ((w,h), d))
@@ -466,8 +463,9 @@
          -> Diagram
 withSize f dia = Compound (Layout (FromSize f) (Identity dia))
 
-diagSize :: Diagram -> Cont Diagram (Double, Double) 
-diagSize d = Cont { runCont = \f -> flip withSize d $ \w h -> f (w, h) } 
+diagSize :: Diagram -> Cont Diagram (Double, Double)
+diagSize d = ContT { runContT = \f -> Identity . flip withSize d $
+                                      \w h -> runIdentity (f (w, h)) }
 
 -- | Align diagrams into a grid, specifying individual alignments for each item.
 --   Warning: there is currently an exponential performace blowup if you nest grids
diff --git a/diagrams.cabal b/diagrams.cabal
--- a/diagrams.cabal
+++ b/diagrams.cabal
@@ -1,5 +1,5 @@
 Name:                diagrams
-Version:             0.2.1.3
+Version:             0.2.2
 Stability:           experimental
 Description:         An embedded domain-specific language (EDSL) for 
                      creating simple diagrams, built on top of the Cairo
@@ -24,7 +24,7 @@
   ghc-options:       -Wall
   if flag(testing)
     ghc-options: -Werror
-  Build-Depends:     base >= 2 && < 5, mtl >= 1.0 && < 1.2,
+  Build-Depends:     base >= 2 && < 5, mtl >= 2.0 && < 2.1,
                      containers >= 0.2 && < 0.4,
                      cairo >= 0.9 && < 0.12, colour >= 2.2.1 && < 2.4
   Exposed-Modules:   Graphics.Rendering.Diagrams,