diff --git a/Kit/Main.hs b/Kit/Main.hs
--- a/Kit/Main.hs
+++ b/Kit/Main.hs
@@ -87,6 +87,7 @@
             writeFile "KitSpec" $ encode verifySpec
             doUpdate
             inDirectory "Kits" $ do
+              system $ "open KitDeps.xcodeproj"
               system $ "xcodebuild -sdk " ++ sdk
           putStrLn "OK."
         puts "End checks."
diff --git a/Kit/Model.hs b/Kit/Model.hs
--- a/Kit/Model.hs
+++ b/Kit/Model.hs
@@ -9,7 +9,9 @@
     specDependencies :: [Kit],
     specSourceDirectory :: FilePath,
     specTestDirectory :: FilePath,
-    specLibDirectory :: FilePath
+    specLibDirectory :: FilePath,
+    specPrefixFile :: FilePath,
+    specConfigFile :: FilePath
   } deriving (Show, Read)
 
   type Version = String
@@ -22,24 +24,22 @@
   kitFileName :: Kit -> String
   kitFileName k = kitName k ++ "-" ++ kitVersion k
 
-  kitConfigFile :: Kit -> String
-  kitConfigFile kit = kitFileName kit </> (kitName kit ++ ".xcconfig")
-
   defaultSpecForKit :: Kit -> KitSpec
-  defaultSpecForKit kit = KitSpec kit [] "src" "test" "lib" -- TODO make this and the json reading use the same defaults
+  defaultSpecForKit kit = KitSpec kit [] "src" "test" "lib" "Prefix.pch" "Config.xcconfig"
+  -- TODO make this and the json reading use the same defaults
+  -- I suspect that to do this I'll need update functions for each of
+  -- fields in the KitSpec record.
+  -- Look at the 'lenses' package on haskell.
 
   instance JSON Kit where
-      showJSON kit = makeObj
-          [ ("name", showJSON $ kitName kit)
-          , ("version", showJSON $ kitVersion kit)
-          ]
+      showJSON kit = makeObj [ ("name", w kitName) , ("version", w kitVersion) ] where w f = showJSON . f $ kit
 
       readJSON (JSObject obj) = Kit <$> f "name" <*> f "version"
         where f x = f' obj x 
 
   instance JSON KitSpec where
-      showJSON spec = makeObj
-          [ ("name", showJSON $ kitName kit)
+      showJSON spec = makeObj [
+            ("name", showJSON $ kitName kit)
           , ("version", showJSON $ kitVersion kit)
           , ("dependencies", showJSON $ specDependencies spec)
           ]
@@ -51,6 +51,8 @@
                       <*> (f "source-directory" <|> pure "src")
                       <*> (f "test-directory" <|> pure "test")
                       <*> (f "lib-directory" <|> pure "lib")
+                      <*> (f "prefix-header" <|> pure "Prefix.pch")
+                      <*> (f "xcconfig" <|> pure "Config.xcconfig")
         where f x = f' obj x
 
   f' obj x = mLookup x (fromJSObject obj) >>= readJSON
diff --git a/Kit/Project.hs b/Kit/Project.hs
--- a/Kit/Project.hs
+++ b/Kit/Project.hs
@@ -47,8 +47,8 @@
         headers = findSrc ".h"
         sources = fmap join $ T.sequence [findSrc ".m", findSrc ".mm", findSrc ".c"]
         libs = find (specLibDirectory spec) ".a" 
-        config = readConfig kit
-        prefix = readHeader kit
+        config = readConfig spec
+        prefix = readHeader spec
     in  KitContents <$> headers <*> sources <*> libs <*> config <*> prefix
 
   generateXCodeProject :: [Kit] -> KitIO ()
@@ -83,18 +83,19 @@
             writeFile xcodeConfigFile $ kitHeaders ++ "\n" ++  prefixHeaders ++ "\n" ++ configToString combinedConfig
             writeFile kitUpdateMakeFilePath kitUpdateMakeFile
 
-  kitPrefixFile = "Prefix.pch"
-
-  readHeader :: Kit -> IO (Maybe String)
-  readHeader kit = do
-    let fp = kitFileName kit </> kitPrefixFile
+  -- Report missing file
+  readHeader :: KitSpec -> IO (Maybe String)
+  readHeader spec = do
+    let fp = (kitFileName . specKit $ spec) </> specPrefixFile spec
     exists <- doesFileExist fp
     contents <- T.sequence (fmap readFile $ justTrue exists fp)
     return contents
 
-  readConfig :: Kit -> IO (Maybe XCConfig)
-  readConfig kit = do
-    let fp = kitConfigFile kit
+  -- TODO make this report missing file
+  readConfig :: KitSpec -> IO (Maybe XCConfig)
+  readConfig spec = do
+    let kit = specKit spec
+    let fp = kitFileName kit </> specConfigFile spec
     exists <- doesFileExist fp
     contents <- T.sequence (fmap readFile $ justTrue exists fp)
     return $ fmap (fileContentsToXCC $ kitName kit) contents
@@ -146,7 +147,5 @@
   readSpecContents kitSpecPath = checkExists kitSpecPath >>= liftIO . readFile
 
   parses :: String -> Either KitError KitSpec
-  parses contents = case (decode contents) of
-                      Ok a -> Right a
-                      Error a -> Left a
+  parses contents = resultToEither (decode contents)
 
diff --git a/kit.cabal b/kit.cabal
--- a/kit.cabal
+++ b/kit.cabal
@@ -1,5 +1,5 @@
 name:           kit
-version:        0.5
+version:        0.5.1
 cabal-version:  >=1.2
 build-type:     Simple
 license:        BSD3