diff --git a/hspec-attoparsec.cabal b/hspec-attoparsec.cabal
--- a/hspec-attoparsec.cabal
+++ b/hspec-attoparsec.cabal
@@ -1,5 +1,5 @@
 name:                hspec-attoparsec
-version:             0.1.0.0
+version:             0.1.0.1
 synopsis:            Utility functions for testing your attoparsec parsers with hspec
 description:         This package provides some helper functions for testing attoparsec parsers with hspec.
                      .
diff --git a/src/Test/Hspec/Attoparsec.hs b/src/Test/Hspec/Attoparsec.hs
--- a/src/Test/Hspec/Attoparsec.hs
+++ b/src/Test/Hspec/Attoparsec.hs
@@ -30,7 +30,6 @@
   ) where
 
 import Control.Monad (when)
-import Data.Either (isLeft, isRight)
 import Test.Hspec.Attoparsec.Source
 import Test.Hspec.Expectations
 
@@ -95,6 +94,14 @@
                 -> Expectation
 parser `shouldSucceedOn` string =
   (string ~> parser) `shouldSatisfy` isRight
+
+isLeft :: Either a b -> Bool
+isLeft (Left _) = True
+isLeft _        = False
+
+isRight :: Either a b -> Bool
+isRight (Right _) = True
+isRight _         = False
 
 -- | Checking that the given parser succeeds
 --   and yields the given part of the input unconsumed.