diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,10 @@
+0.1.1.1
+-------
+<https://github.com/mstksg/prompt/releases/tag/v0.1.1.1>
+
+*   Removed redundant `Error` constraint on `MonadPrompt` instance for
+    `ErrorT`.
+
 0.1.1.0
 -------
 <https://github.com/mstksg/prompt/releases/tag/v0.1.1.0>
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,6 +1,13 @@
 prompt
 ======
 
+[![prompt on Stackage LTS 2](http://stackage.org/package/prompt/badge/lts-2)](http://stackage.org/lts-2/package/prompt)
+[![prompt on Stackage LTS 3](http://stackage.org/package/prompt/badge/lts-3)](http://stackage.org/lts-3/package/prompt)
+[![prompt on Stackage LTS 4](http://stackage.org/package/prompt/badge/lts-4)](http://stackage.org/lts-4/package/prompt)
+[![prompt on Stackage LTS](http://stackage.org/package/prompt/badge/lts)](http://stackage.org/lts/package/prompt)
+[![prompt on Stackage Nightly](http://stackage.org/package/prompt/badge/nightly)](http://stackage.org/nightly/package/prompt)
+
+
 Lightweight library providing a monad/applicative (and transformer) for
 delayed-effect "pure" prompt-and-respose queries.
 
diff --git a/prompt.cabal b/prompt.cabal
--- a/prompt.cabal
+++ b/prompt.cabal
@@ -2,7 +2,7 @@
 --  see http://haskell.org/cabal/users-guide/
 
 name:                prompt
-version:             0.1.1.0
+version:             0.1.1.1
 synopsis:            Monad (and transformer) for deferred-effect pure
                      prompt-response queries
 description:         Monad (and transformer) for delayed-effect "pure"
@@ -49,6 +49,7 @@
   -- other-modules:       
   -- other-extensions:    
   build-depends:       base >=4.6 && <5
+                     , base-compat
                      , mtl
                      , transformers
                      , transformers-compat
diff --git a/src/Control/Monad/Prompt.hs b/src/Control/Monad/Prompt.hs
--- a/src/Control/Monad/Prompt.hs
+++ b/src/Control/Monad/Prompt.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE UndecidableInstances #-}
@@ -61,7 +62,7 @@
   ) where
 
 import Control.Applicative
-import Control.Monad hiding       (sequence, mapM, msum)
+import Control.Monad.Compat hiding (sequence, mapM, msum)
 import Control.Monad.Error.Class
 import Control.Monad.Prompt.Class
 import Control.Monad.Reader.Class
@@ -70,11 +71,7 @@
 import Control.Monad.Writer.Class
 import Data.Foldable
 import Data.Functor.Identity
-
-#if !MIN_VERSION_base(4,8,0)
-import Data.Traversable
-import Prelude hiding (sequence, mapM)
-#endif
+import Prelude.Compat
 
 
 -- | Like 'Prompt', but can perform its "pure" computations in the context
@@ -307,6 +304,8 @@
 -- 'Prompt' itself in general has nothing to do with @m@, and cannot
 -- execute arbitrary @m@ other than that given in the prompt response
 -- function.
+--
+-- Effectively treats a @'Prompt' a b@ as a @forall m. ReaderT (a -> m b) m@
 runPromptM :: Monad m
            => Prompt a b r
            -> (a -> m b)   -- ^ "Prompt response function", effectfully
diff --git a/src/Control/Monad/Prompt/Class.hs b/src/Control/Monad/Prompt/Class.hs
--- a/src/Control/Monad/Prompt/Class.hs
+++ b/src/Control/Monad/Prompt/Class.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE FunctionalDependencies #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE UndecidableInstances #-}
 {-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}
 
@@ -42,6 +43,7 @@
 import Control.Monad.Trans.Except
 import Control.Monad.Trans.Maybe
 import Control.Monad.Trans.Reader
+import Prelude.Compat
 import qualified Control.Monad.Trans.RWS.Lazy      as RWSL
 import qualified Control.Monad.Trans.RWS.Strict    as RWSS
 import qualified Control.Monad.Trans.State.Lazy    as SL
@@ -49,10 +51,6 @@
 import qualified Control.Monad.Trans.Writer.Lazy   as WL
 import qualified Control.Monad.Trans.Writer.Strict as WS
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative
-import Data.Monoid
-#endif
 
 -- | An 'Applicative' (and possibly 'Monad') where you can, at any time,
 -- "prompt" with an @a@ and receive a @b@ in response.
@@ -90,7 +88,7 @@
     prompt    = lift . prompt
     prompts f = lift . prompts f
 
-instance (Monad m, MonadPrompt a b m, Error e) => MonadPrompt a b (ErrorT e m) where
+instance (Monad m, MonadPrompt a b m) => MonadPrompt a b (ErrorT e m) where
     prompt    = lift . prompt
     prompts f = lift . prompts f