diff --git a/src/Control/Monad/TestFixture.hs b/src/Control/Monad/TestFixture.hs
--- a/src/Control/Monad/TestFixture.hs
+++ b/src/Control/Monad/TestFixture.hs
@@ -1,6 +1,9 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE UndecidableInstances #-}
 
 #if __GLASGOW_HASKELL__ >= 800
 {-# OPTIONS_GHC -fno-warn-redundant-constraints #-}
@@ -160,7 +163,7 @@
   > instance Monoid log => LookupUser (TestFixture Fixture log state) where
   >   lookupUser userId = do
   >     fn <- asks _lookupUser
-  >     lift $ fn userId
+  >     fn userId
 
   Now we can write our tests using the 'unTestFixture' function, along with the
   similar 'logTestFixture' functions and friends:
@@ -219,6 +222,7 @@
 import qualified Control.Monad.Writer.Class
 import qualified Control.Monad.State.Class
 
+import Control.Monad.Error.Class
 import Control.Monad.RWS
 import Data.Functor.Identity
 
@@ -242,6 +246,10 @@
 instance MonadTrans (TestFixtureT fixture log state) where
   lift = TestFixtureT . lift
 
+instance MonadError e m => MonadError e (TestFixtureT fixture log state m) where
+  throwError = lift . throwError
+  catchError m h = TestFixtureT (getRWST m `catchError` \e -> getRWST (h e))
+
 -- | The transformer equivalent of 'unTestFixture'.
 unTestFixtureT :: Monad m => TestFixtureT fixture () () m a -> fixture (TestFixtureT fixture () () m) -> m a
 unTestFixtureT stack env = fmap fst (evalTestFixtureT stack env)
@@ -313,7 +321,7 @@
   > instance Monoid log => MonadSomething (TestFixture Fixture log state) where
   >   getSomething = do
   >     something <- asks _getSomething
-  >     lift something
+  >     something
 
   Using 'arg0', it can be rewritten like this:
 
@@ -333,7 +341,7 @@
   > instance Monoid log => MonadSomething (TestFixture Fixture log state) where
   >   doSomething x = do
   >     fn <- asks _doSomething
-  >     lift $ fn x
+  >     fn x
 
   Using 'arg1', it can be rewritten like this:
 
diff --git a/src/Control/Monad/TestFixture/TH.hs b/src/Control/Monad/TestFixture/TH.hs
--- a/src/Control/Monad/TestFixture/TH.hs
+++ b/src/Control/Monad/TestFixture/TH.hs
@@ -59,33 +59,27 @@
   >     }
   >
   > type FixturePure = Fixture (TestFixture Fixture () ())
-  >
   > type FixtureLog log = Fixture (TestFixture Fixture log ())
-  >
   > type FixtureState state = Fixture (TestFixture Fixture () state)
-  >
   > type FixtureLogState log state = Fixture (TestFixture Fixture log state)
   >
   > type FixturePureT m = Fixture (TestFixture Fixture () () m)
-  >
   > type FixtureLogT log m = Fixture (TestFixture Fixture log () m)
-  >
   > type FixtureStateT state m = Fixture (TestFixture Fixture () state m)
-  >
   > type FixtureLogStateT log state m = Fixture (TestFixtureT Fixture log state m)
   >
   > instance Monad m => DB (TestFixtureT Fixture w s m) where
   >   fetchRecord r = do
   >     fn <- asks _fetchRecord
-  >     lift $ fn r
+  >     fn r
   >   insertRecord r = do
   >     fn <- asks _insertRecord
-  >     lift $ fn r
+  >     fn r
   >
   > instance Monad m => HTTP (TestFixtureT Fixture w s m) where
   >   sendRequest r = do
   >     fn <- asks _sendRequest
-  >     lift $ fn r
+  >     fn r
 
   This type can then be used in tandem with "Control.Monad.TestFixture" to
   create stubbed typeclass instances and run computations using them.
diff --git a/test-fixture.cabal b/test-fixture.cabal
--- a/test-fixture.cabal
+++ b/test-fixture.cabal
@@ -1,7 +1,7 @@
 name:
   test-fixture
 version:
-  0.4.0.0
+  0.4.1.0
 synopsis:
   Test monadic side-effects
 description: