diff --git a/mnist-idx.cabal b/mnist-idx.cabal
--- a/mnist-idx.cabal
+++ b/mnist-idx.cabal
@@ -1,6 +1,6 @@
 name:                mnist-idx
 
-version:             0.1.2.7
+version:             0.1.2.8
 
 -- A short (one-line) description of the package.
 synopsis:            Read and write IDX data that is used in e.g. the MNIST database.
@@ -38,7 +38,7 @@
 -- extra-source-files:  
 
 -- Constraint on the version of Cabal needed to build this package.
-cabal-version:       >= 1.16
+cabal-version:       >= 1.10
 
 source-repository head
   type:              git
@@ -56,6 +56,7 @@
   -- other-extensions:    
   
   -- Other library packages from which modules are imported.
+  default-language:    Haskell2010
   build-depends:       base >=4.6 && <5,
                        binary >= 0.7 && < 0.9,
                        vector >= 0.10 && < 0.13,
diff --git a/src/Data/IDX/Internal.hs b/src/Data/IDX/Internal.hs
--- a/src/Data/IDX/Internal.hs
+++ b/src/Data/IDX/Internal.hs
@@ -23,6 +23,7 @@
 
 import qualified Data.Vector.Unboxed as V
 import           Data.Vector.Unboxed ((!))
+import           Data.Functor ((<$>))
 
 -- | A type to describe the content, according to IDX spec
 data IDXContentType where