diff --git a/hnix-store-nar/src/System/Nix/Nar/Effects.hs b/hnix-store-nar/src/System/Nix/Nar/Effects.hs
index 95be4eb..50f9870 100644
--- a/hnix-store-nar/src/System/Nix/Nar/Effects.hs
+++ b/hnix-store-nar/src/System/Nix/Nar/Effects.hs
@@ -3,11 +3,13 @@
 module System.Nix.Nar.Effects
   ( NarEffects(..)
   , narEffectsIO
+  , IsExecutable(..)
   ) where
 
 import Control.Monad.Trans.Control (MonadBaseControl)
 import Control.Monad.IO.Class (MonadIO(liftIO))
 import Data.ByteString (ByteString)
+import Data.Bool (bool)
 import Data.Int (Int64)
 import Data.Kind (Type)
 import System.IO (Handle, IOMode(WriteMode))
@@ -25,15 +27,17 @@ import           System.Posix.Files          ( createSymbolicLink
 import qualified System.IO                   as IO
 import qualified Control.Exception.Lifted    as Exception.Lifted
 
+data IsExecutable = NonExecutable | Executable
+  deriving (Eq, Show)
+
 data NarEffects (m :: Type -> Type) = NarEffects {
     narReadFile   :: FilePath -> m Bytes.Lazy.ByteString
-  , narWriteFile  :: FilePath -> Bytes.Lazy.ByteString -> m ()
-  , narStreamFile :: FilePath -> m (Maybe ByteString) -> m ()
+  , narWriteFile  :: FilePath -> IsExecutable -> Bytes.Lazy.ByteString -> m ()
+  , narStreamFile :: FilePath -> IsExecutable -> m (Maybe ByteString) -> m ()
   , narListDir    :: FilePath -> m [FilePath]
   , narCreateDir  :: FilePath -> m ()
   , narCreateLink :: FilePath -> FilePath -> m ()
-  , narGetPerms   :: FilePath -> m Directory.Permissions
-  , narSetPerms   :: FilePath -> Directory.Permissions ->  m ()
+  , narIsExec     :: FilePath -> m IsExecutable
   , narIsDir      :: FilePath -> m Bool
   , narIsSymLink  :: FilePath -> m Bool
   , narFileSize   :: FilePath -> m Int64
@@ -53,13 +57,15 @@ narEffectsIO
   => NarEffects m
 narEffectsIO = NarEffects {
     narReadFile   = liftIO . Bytes.Lazy.readFile
-  , narWriteFile  = \a -> liftIO . Bytes.Lazy.writeFile a
+  , narWriteFile  = \f e c -> liftIO $ do
+      Bytes.Lazy.writeFile f c
+      p <- Directory.getPermissions f
+      Directory.setPermissions f (p { Directory.executable = e == Executable })
   , narStreamFile = streamStringOutIO
   , narListDir    = liftIO . Directory.listDirectory
   , narCreateDir  = liftIO . Directory.createDirectory
   , narCreateLink = \f -> liftIO . createSymbolicLink f
-  , narGetPerms   = liftIO . Directory.getPermissions
-  , narSetPerms   = \f -> liftIO . Directory.setPermissions f
+  , narIsExec     = liftIO . (fmap (bool NonExecutable Executable . Directory.executable)) . Directory.getPermissions
   , narIsDir      = fmap isDirectory . liftIO . getFileStatus
   , narIsSymLink  = liftIO . Directory.pathIsSymbolicLink
   , narFileSize   = fmap (fromIntegral . fileSize) . liftIO . getFileStatus
@@ -76,9 +82,10 @@ streamStringOutIO
      , MonadBaseControl IO m
      )
   => FilePath
+  -> IsExecutable
   -> m (Maybe ByteString)
   -> m ()
-streamStringOutIO f getChunk =
+streamStringOutIO f executable getChunk =
   Exception.Lifted.bracket
     (liftIO $ IO.openFile f WriteMode)
     (liftIO . IO.hClose)
@@ -93,6 +100,9 @@ streamStringOutIO f getChunk =
       Nothing -> pure ()
       Just c  -> do
         liftIO $ Data.ByteString.hPut handle c
+        Control.Monad.when (executable == Executable) $ liftIO $ do
+          p <- Directory.getPermissions f
+          Directory.setPermissions f (p { Directory.executable = True })
         go handle
   cleanupException (e :: Exception.Lifted.SomeException) = do
     liftIO $ Directory.removeFile f
diff --git a/hnix-store-nar/src/System/Nix/Nar/Parser.hs b/hnix-store-nar/src/System/Nix/Nar/Parser.hs
index 2feb6c5..1a6650f 100644
--- a/hnix-store-nar/src/System/Nix/Nar/Parser.hs
+++ b/hnix-store-nar/src/System/Nix/Nar/Parser.hs
@@ -268,13 +268,8 @@ parseFile = do
 
   target     <- currentFile
   streamFile <- getNarEffect Nar.narStreamFile
-  Trans.lift (streamFile target getChunk)
-
-  when (s == "executable") $ do
-    effs :: Nar.NarEffects m <- getNarEffects
-    Trans.lift $ do
-      p <- Nar.narGetPerms effs target
-      Nar.narSetPerms effs target (p { Directory.executable = True })
+  let isExecutable = bool Nar.NonExecutable Nar.Executable (s == "executable")
+  Trans.lift (streamFile target isExecutable getChunk)
 
   expectRawString (Bytes.replicate (padLen $ fromIntegral fSize) 0)
 
diff --git a/hnix-store-nar/src/System/Nix/Nar/Streamer.hs b/hnix-store-nar/src/System/Nix/Nar/Streamer.hs
index 28aadf1..08f92a1 100644
--- a/hnix-store-nar/src/System/Nix/Nar/Streamer.hs
+++ b/hnix-store-nar/src/System/Nix/Nar/Streamer.hs
@@ -7,7 +7,7 @@ module System.Nix.Nar.Streamer
   , dumpPath
   , streamNarIO
   , streamNarIOWithOptions
-  , IsExecutable(..)
+  , Nar.IsExecutable(..)
   ) where
 
 import Data.ByteString (ByteString)
@@ -18,7 +18,6 @@ import           Control.Monad                    ( forM_
                                                   , when
                                                   )
 import qualified Control.Monad.IO.Class          as IO
-import           Data.Bool                        ( bool )
 import qualified Data.ByteString                 as Bytes
 import qualified Data.ByteString.Lazy            as Bytes.Lazy
 import qualified Data.Foldable
@@ -26,7 +25,6 @@ import qualified Data.List
 import qualified Data.Serialize                  as Serial
 import qualified Data.Text                       as T (pack, breakOn)
 import qualified Data.Text.Encoding              as TE (encodeUtf8)
-import qualified System.Directory                as Directory
 import           System.FilePath                 ((</>))
 
 import qualified System.Nix.Nar.Effects as Nar
@@ -107,9 +105,9 @@ streamNarIOWithOptions opts effs basePath yield = do
               yield $ strs ["name", serializedPath, "node"]
               parens $ go fullName
         else do
-          isExec <- IO.liftIO $ isExecutable effs path
+          isExec <- IO.liftIO $ Nar.narIsExec effs path
           yield $ strs ["type", "regular"]
-          when (isExec == Executable) $ yield $ strs ["executable", ""]
+          when (isExec == Nar.Executable) $ yield $ strs ["executable", ""]
           fSize <- IO.liftIO $ Nar.narFileSize effs path
           yield $ str "contents"
           yield $ int fSize
@@ -127,20 +125,6 @@ streamNarIOWithOptions opts effs basePath yield = do
     mapM_ yield . Bytes.Lazy.toChunks =<< IO.liftIO (Nar.narReadFile effs path)
     yield $ Bytes.replicate (padLen $ fromIntegral fsize) 0
 
-data IsExecutable = NonExecutable | Executable
-  deriving (Eq, Show)
-
-isExecutable
-  :: Functor m
-  => Nar.NarEffects m
-  -> FilePath
-  -> m IsExecutable
-isExecutable effs fp =
-  bool
-    NonExecutable
-    Executable
-    . Directory.executable <$> Nar.narGetPerms effs fp
-
 -- | Distance to the next multiple of 8
 padLen :: Int -> Int
 padLen n = (8 - n) `mod` 8