diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -193,9 +193,9 @@
 defConfig = PGConfig "localhost" 5432
 
 main :: IO ()
-main =
+main = do
   _ <- setEnv "PG_HOST" "customURL" True
-  print =<< decodeWithDefaults defConfig :: IO (Either String PGConfig)
+  print =<< decodeWithDefaults defConfig
  -- > PGConfig { pgHost = "customURL", pgPort = 5432 }
 ```
 
diff --git a/envy.cabal b/envy.cabal
--- a/envy.cabal
+++ b/envy.cabal
@@ -1,5 +1,5 @@
 name:                envy
-version:             2.1.2.0
+version:             2.1.3.0
 synopsis:            An environmentally friendly way to deal with environment variables
 license:             BSD3
 license-file:        LICENSE
@@ -21,10 +21,10 @@
   ghc-options:          -Wall
   hs-source-dirs:       src
   build-depends:        base         >= 4.11 && < 5
-                      , bytestring   == 0.10.* || == 0.11.*
+                      , bytestring   >= 0.10 && < 0.13
                       , containers   >= 0.5 && < 0.7
                       , mtl          == 2.2.* || == 2.3.*
-                      , text         == 1.2.* || == 2.0.*
+                      , text         == 1.2.* || >= 2.0 && <2.2
                       , time         >= 1.5 && < 2.0
                       , transformers >= 0.4 && < 0.7
   default-language:     Haskell2010
diff --git a/src/System/Envy.hs b/src/System/Envy.hs
--- a/src/System/Envy.hs
+++ b/src/System/Envy.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE DeriveGeneric              #-}
 {-# LANGUAGE RecordWildCards            #-}
 {-# LANGUAGE StandaloneDeriving         #-}
 {-# LANGUAGE TypeOperators              #-}
@@ -89,6 +88,7 @@
 import           Data.Monoid
 import           Data.Char
 import           Data.Time
+import           Data.Kind
 import           GHC.Generics
 import           Data.Typeable
 import           System.Environment.Blank
@@ -267,7 +267,7 @@
       snake :: String -> String
       snake = map toUpper . snakeCase
 
-data SelectorProxy (s :: Meta) (f :: * -> *) a = SelectorProxy
+data SelectorProxy (s :: Meta) (f :: Type -> Type) a = SelectorProxy
 
 ------------------------------------------------------------------------------
 -- | Type class for objects which can be converted to a set of
@@ -350,7 +350,7 @@
 ------------------------------------------------------------------------------
 -- | Environment retrieval with default values provided
 decodeWithDefaults :: FromEnv a => a -> IO a
-decodeWithDefaults def = (\(Right x) -> x) <$> evalParser (fromEnv (Just def))
+decodeWithDefaults def = either error pure =<< evalParser (fromEnv (Just def))
 
 ------------------------------------------------------------------------------
 -- | Catch an IO exception and return it in an Either.