diff --git a/Control/Monad/Readers.hs b/Control/Monad/Readers.hs
--- a/Control/Monad/Readers.hs
+++ b/Control/Monad/Readers.hs
@@ -12,6 +12,7 @@
 import qualified Control.Monad.Reader as MTL (ask, local)
 import Control.Monad.State (StateT, mapStateT)
 import Control.Monad.Writer (WriterT, mapWriterT)
+import Data.Monoid (Monoid)
 
 -- | Version of MonadReader modified to remove the functional dependency.
 class Monad m => MonadReaders r m where
diff --git a/Control/Monad/States.hs b/Control/Monad/States.hs
--- a/Control/Monad/States.hs
+++ b/Control/Monad/States.hs
@@ -13,6 +13,7 @@
 import Control.Monad.State hiding (MonadState(get, put, state), modify, modify', gets)
 import qualified Control.Monad.State as MTL (get, put)
 import Control.Monad.Writer (WriterT)
+import Data.Monoid (Monoid)
 
 -- | Copy of 'Control.Monad.State.MonadState' with functional dependency m -> s removed.
 class Monad m => MonadStates s m where
diff --git a/mtl-unleashed.cabal b/mtl-unleashed.cabal
--- a/mtl-unleashed.cabal
+++ b/mtl-unleashed.cabal
@@ -1,5 +1,5 @@
 name:               mtl-unleashed
-version:            0.2.1
+version:            0.2.2
 cabal-version:      >= 1.10
 build-type:         Simple
 license:            BSD3