Including data files in cabal builds

I have a package with the following structure (okay, this is greatly simplified, but...) ``` app/ src/ Main.hs data/ data.txt app.cabal Paths_app.hs Setup.hs ``` In Paths_app.hs I have: ``` module Paths_app where getDataFileName :: FilePath -> IO FilePath getDataFileName = return ``` and in Main.hs I have: ``` module Main where import Paths_app main = do file <- getDataFileName "data/data.txt" data <- readFile file putStrLn $ "Your data is: " ++ data ``` the relevant parts of my app.cabal file look like this: ``` name: app version: 1.0 build-type: Simple data-files: data/data.txt executable foo build-depends: base, haskell98 main-is: Main.hs hs-source-dirs: src ``` This builds fine (using `cabal configure` followed by `cabal install`) but the executable complains that it can't find the data.txt file. I've tried replacing the line ``` file <- getDataFileName "data/data.txt" ``` with ``` file <- getDataFileName "data.txt" ``` but the same thing occurs. Is there something obvious I'm doing wrong?