diff --git a/ghc-mod.cabal b/ghc-mod.cabal
index 9ea9352..ed5d6f7 100644
--- a/ghc-mod.cabal
+++ b/ghc-mod.cabal
@@ -88,7 +88,8 @@ Library
 Executable ghc-mod
   Default-Language:     Haskell2010
   Main-Is:              GHCMod.hs
-  Other-Modules:        Paths_ghc_mod
+  Other-Modules:        Boot
+                        Paths_ghc_mod
   GHC-Options:          -Wall
   HS-Source-Dirs:       src
   Build-Depends:        base >= 4.0 && < 5
@@ -100,7 +101,8 @@ Executable ghc-mod
 Executable ghc-modi
   Default-Language:     Haskell2010
   Main-Is:              GHCModi.hs
-  Other-Modules:        Paths_ghc_mod
+  Other-Modules:        Boot
+                        Paths_ghc_mod
   GHC-Options:          -Wall
   HS-Source-Dirs:       src
   Build-Depends:        base >= 4.0 && < 5
diff --git a/src/Boot.hs b/src/Boot.hs
new file mode 100644
index 0000000..cf0ea66
--- /dev/null
+++ b/src/Boot.hs
@@ -0,0 +1,42 @@
+module Boot where
+
+import Language.Haskell.GhcMod
+import Control.Applicative ((<$>))
+
+boot :: Options -> Cradle -> IO String
+boot opt cradle = do
+    mods  <- listModules opt cradle
+    langs <- listLanguages opt
+    flags <- listFlags opt
+    let opt' = addPackages opt
+    pre   <- concat <$> mapM (browseModule opt' cradle) preBrowsedModules
+    return $ mods ++ langs ++ flags ++ pre
+
+preBrowsedModules :: [String]
+preBrowsedModules = [
+    "Prelude"
+  , "Control.Applicative"
+  , "Control.Exception"
+  , "Control.Monad"
+  , "Data.ByteString"
+  , "Data.Char"
+  , "Data.List"
+  , "Data.Maybe"
+  , "System.Directory"
+  , "System.FilePath"
+  , "System.IO"
+  ]
+
+preBrowsePackages :: [String]
+preBrowsePackages = [
+    "bytestring"
+  , "directory"
+  , "filepath"
+  ]
+
+addPackages :: Options -> Options
+addPackages opt = opt { ghcOpts = pkgs ++ ghcOpts opt}
+  where
+    pkgs = map ("-package " ++) preBrowsePackages
+
+
diff --git a/src/GHCMod.hs b/src/GHCMod.hs
index 9771ff2..f19734e 100644
--- a/src/GHCMod.hs
+++ b/src/GHCMod.hs
@@ -16,6 +16,8 @@ import System.Environment (getArgs)
 import System.Exit (exitFailure)
 import System.IO (hPutStr, hPutStrLn, stdout, stderr, hSetEncoding, utf8)
 
+import Boot
+
 ----------------------------------------------------------------
 
 ghcOptHelp :: String
@@ -118,13 +120,7 @@ main = flip E.catches handlers $ do
       "lint"   -> nArgs 1 withFile (lintSyntax opt) cmdArg1
       "root"   -> rootInfo opt cradle
       "doc"    -> nArgs 1 $ packageDoc opt cradle cmdArg1
-      "boot"   -> do
-         mods  <- listModules opt cradle
-         langs <- listLanguages opt
-         flags <- listFlags opt
-         let opt' = addPackages opt
-         pre   <- concat <$> mapM (browseModule opt' cradle) preBrowsedModules
-         return $ mods ++ langs ++ flags ++ pre
+      "boot"   -> boot opt cradle
       "help"   -> return $ O.usageInfo usage argspec
       cmd      -> E.throw (NoSuchCommand cmd)
     putStr res
@@ -156,32 +152,3 @@ main = flip E.catches handlers $ do
     xs !. idx
       | length xs <= idx = E.throw SafeList
       | otherwise = xs !! idx
-
-----------------------------------------------------------------
-
-preBrowsedModules :: [String]
-preBrowsedModules = [
-    "Prelude"
-  , "Control.Applicative"
-  , "Control.Exception"
-  , "Control.Monad"
-  , "Data.ByteString"
-  , "Data.Char"
-  , "Data.List"
-  , "Data.Maybe"
-  , "System.Directory"
-  , "System.FilePath"
-  , "System.IO"
-  ]
-
-preBrowsePackages :: [String]
-preBrowsePackages = [
-    "bytestring"
-  , "directory"
-  , "filepath"
-  ]
-
-addPackages :: Options -> Options
-addPackages opt = opt { ghcOpts = pkgs ++ ghcOpts opt}
-  where
-    pkgs = map ("-package " ++) preBrowsePackages