diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# dyckword
+# dyckword [![Build Status](https://img.shields.io/travis/johanneshilden/dyckword/master.svg?style=flat)](https://travis-ci.org/johanneshilden/dyckword)
 
 In formal language theory, the *Dyck language* consists of all strings of evenly balanced left and right parentheses, brackets, or some other symbols, together with the *empty* word. Words in this language (named after German mathematician Walther von Dyck) are known as *Dyck words*, some examples of which are `()()()`, `(())((()))`, and `((()()))()`.
 
@@ -10,3 +10,4 @@
 E.g., `(()(()` and `())(())()` are **not** Dyck words.
 
 When regarded as a combinatorial class – with the size of a word defined as the number of bracket pairs it contains – the counting sequence associated with the Dyck language is the *Catalan numbers*.
+
diff --git a/dyckword.cabal b/dyckword.cabal
--- a/dyckword.cabal
+++ b/dyckword.cabal
@@ -1,5 +1,5 @@
 name:                dyckword
-version:             0.1.0.2
+version:             0.1.0.3
 synopsis:            A library for working with binary Dyck words.
 description:
     The binary Dyck language consists of all strings of evenly balanced left 
@@ -26,7 +26,7 @@
   hs-source-dirs:      src
   exposed-modules:     Math.DyckWord.Binary
                      , Math.DyckWord.Binary.Internal
-  build-depends:       base >= 4.7 && < 5
+  build-depends:       base ==4.*
                      , text
                      , exact-combinatorics
   default-language:    Haskell2010
diff --git a/src/Math/DyckWord/Binary.hs b/src/Math/DyckWord/Binary.hs
--- a/src/Math/DyckWord/Binary.hs
+++ b/src/Math/DyckWord/Binary.hs
@@ -78,8 +78,9 @@
   , wordsOfSize 
   ) where
 
+import Control.Applicative                 ( (<$>) )
 import Data.Maybe                          ( fromJust )
-import Data.Monoid                         ( (<>) )
+import Data.Monoid
 import Data.Text                           ( Text, unfoldrN )
 import Math.DyckWord.Binary.Internal
 
diff --git a/src/Math/DyckWord/Binary/Internal.hs b/src/Math/DyckWord/Binary/Internal.hs
--- a/src/Math/DyckWord/Binary/Internal.hs
+++ b/src/Math/DyckWord/Binary/Internal.hs
@@ -1,5 +1,6 @@
 module Math.DyckWord.Binary.Internal where
 
+import Control.Applicative                    ( (<$>) )
 import Math.Combinatorics.Exact.Binomial
 
 catalanTriangle :: Integer -> Integer -> Integer
diff --git a/tests/Suite.hs b/tests/Suite.hs
--- a/tests/Suite.hs
+++ b/tests/Suite.hs
@@ -2,7 +2,6 @@
 module Main where
 
 import Control.Monad ( forM_ )
-import Data.Either   ( isLeft )
 import Data.Monoid   ( (<>) )
 import System.Console.ANSI
 import System.Exit   ( exitFailure )
@@ -13,6 +12,10 @@
 import Math.DyckWord.Binary.Internal
 
 import qualified Data.Text as T
+
+isLeft :: Either a b -> Bool
+isLeft (Left  _) = True
+isLeft (Right _) = False
 
 lastN :: Int -> [a] -> [a]
 lastN n xs = drop (length xs - n) xs