diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2015 Alexander Thiemann
+Copyright (c) 2015-2021 Alexander Thiemann
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -78,10 +78,9 @@
 
 ### Supported GHC Versions
 
-* 7.8.4
-* 7.10.2
+* 8.8.4
 
 ### License
 
 Released under the MIT license.
-(c) 2015 Alexander Thiemann
+(c) 2015-2021 Alexander Thiemann
diff --git a/src/Data/Validator.hs b/src/Data/Validator.hs
--- a/src/Data/Validator.hs
+++ b/src/Data/Validator.hs
@@ -30,22 +30,22 @@
 import Control.Monad
 import Control.Monad.Identity
 import Control.Monad.Trans
-import Control.Monad.Trans.Either
+import Control.Monad.Trans.Except
 import Data.Int
 import Data.String.Conversions
 import Text.Regex.PCRE.Heavy
+import qualified Data.ByteString as BS
+import qualified Data.ByteString.Lazy as BSL
 import qualified Data.List.NonEmpty as NEL
 import qualified Data.Text as T
 import qualified Data.Text.Lazy as TL
-import qualified Data.ByteString as BS
-import qualified Data.ByteString.Lazy as BSL
 
 -- | The validation monad
 type ValidationM e = ValidationT e Identity
 
 -- | The validation monad transformer
 newtype ValidationT e m a
-    = ValidationT { unValidationT :: EitherT e m a }
+    = ValidationT { unValidationT :: ExceptT e m a }
       deriving (Monad, Functor, Applicative, Alternative, MonadPlus, MonadTrans)
 
 -- | Run a validation on a type 'a'
@@ -56,7 +56,7 @@
 -- | Run a validation on a type 'a'
 runValidatorT :: Monad m => TransValidationRuleT e m a b -> a -> m (Either e b)
 runValidatorT validationSteps input =
-    runEitherT $ unValidationT (validationSteps input)
+    runExceptT $ unValidationT (validationSteps input)
 {-# INLINE runValidatorT #-}
 
 -- | A validation rule. Combine using @('>=>')@ or @('<=<')@
@@ -97,7 +97,7 @@
 
 -- | Mark a custom check as failed
 checkFailed :: Monad m => e -> ValidationT e m a
-checkFailed = ValidationT . left
+checkFailed = ValidationT . throwE
 {-# INLINE checkFailed #-}
 
 -- | Check that the value is at least N elements long
diff --git a/validate-input.cabal b/validate-input.cabal
--- a/validate-input.cabal
+++ b/validate-input.cabal
@@ -1,5 +1,5 @@
 name:                validate-input
-version:             0.4.0.0
+version:             0.5.0.0
 synopsis:            Input validation combinator library
 description:         A small Haskell combinator library that provides a simple way of
                      validating user provided data structures.
@@ -9,12 +9,12 @@
 license-file:        LICENSE
 author:              Alexander Thiemann <mail@athiemann.net>
 maintainer:          Alexander Thiemann <mail@athiemann.net>
-copyright:           (c) 2015 Alexander Thiemann
+copyright:           (c) 2015-2021 Alexander Thiemann
 category:            Web
 build-type:          Simple
 cabal-version:       >=1.10
 tested-with:
-    GHC == 7.8.4, GHC == 7.10.2
+    GHC == 8.8.4
 
 extra-source-files:
     README.md
@@ -28,7 +28,7 @@
   build-depends:
                        base >=4.6 && <5,
                        bytestring >=0.10,
-                       either >=4.3,
+                       transformers,
                        mtl >=2.1,
                        pcre-heavy >=1.0,
                        string-conversions >=0.4,
@@ -36,7 +36,7 @@
                        text >=1.2
   hs-source-dirs:      src
   default-language:    Haskell2010
-  ghc-options:         -auto-all -Wall -fno-warn-orphans
+  ghc-options:         -Wall -fno-warn-orphans
 
 test-suite validate-input-tests
   type:                exitcode-stdio-1.0
@@ -47,5 +47,5 @@
                        hspec >=2.1,
                        QuickCheck >=2.7,
                        validate-input
-  ghc-options:         -auto-all -Wall -fno-warn-orphans
+  ghc-options:         -Wall -fno-warn-orphans
   default-language:    Haskell2010