diff --git a/app/Niv.hs b/app/Niv.hs
index 2603ab0..22a7b6d 100644
--- a/app/Niv.hs
+++ b/app/Niv.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -11,6 +12,7 @@ import Control.Monad
 import Control.Monad.State
 import Data.Aeson (FromJSON, FromJSONKey, ToJSON, ToJSONKey)
 import Data.Char (isSpace, toUpper)
+import Data.FileEmbed (embedFile)
 import Data.Functor ((<&>))
 import Data.Hashable (Hashable)
 import Data.Maybe (mapMaybe, fromMaybe)
@@ -23,6 +25,7 @@ import UnliftIO
 import qualified Data.Aeson as Aeson
 import qualified Data.Aeson.Encode.Pretty as AesonPretty
 import qualified Data.ByteString as B
+import qualified Data.ByteString.Char8 as B8
 import qualified Data.ByteString.Lazy as L
 import qualified Data.HashMap.Strict as HMap
 import qualified Data.Text as T
@@ -319,7 +322,7 @@ cmdInit = do
             if shouldUpdateNixSourcesNix content
             then do
               putStrLn "Updating sources.nix"
-              writeFile path initNixSourcesNixContent
+              B.writeFile path initNixSourcesNixContent
             else putStrLn "Not updating sources.nix"
         )
       , ( pathNixSourcesJson
@@ -336,14 +339,14 @@ cmdInit = do
         , \path _content -> dontCreateFile path)
       ] $ \(path, onCreate, onUpdate) -> do
           exists <- Dir.doesFileExist path
-          if exists then readFile path >>= onUpdate path else onCreate path
+          if exists then B.readFile path >>= onUpdate path else onCreate path
   where
-    createFile :: FilePath -> String -> IO ()
+    createFile :: FilePath -> B.ByteString -> IO ()
     createFile path content = do
       let dir = takeDirectory path
       Dir.createDirectoryIfMissing True dir
       putStrLn $ "Creating " <> path
-      writeFile path content
+      B.writeFile path content
     dontCreateFile :: FilePath -> IO ()
     dontCreateFile path = putStrLn $ "Not creating " <> path
 
@@ -611,24 +614,24 @@ nixPrefetchURL unpack url =
 
 -- | Checks if content is different than default and if it does /not/ contain
 -- a comment line with @niv: no_update@
-shouldUpdateNixSourcesNix :: String -> Bool
+shouldUpdateNixSourcesNix :: B.ByteString -> Bool
 shouldUpdateNixSourcesNix content =
     content /= initNixSourcesNixContent &&
-      not (any lineForbids (lines content))
+      not (any lineForbids (B8.lines content))
   where
-    lineForbids :: String -> Bool
+    lineForbids :: B8.ByteString -> Bool
     lineForbids str =
-      case dropWhile isSpace str of
-        '#':rest -> case dropWhile isSpace rest of
-          'n':'i':'v':':':rest' -> case dropWhile isSpace rest' of
-            'n':'o':'_':'u':'p':'d':'a':'t':'e':_ -> True
+      case B8.uncons (B8.dropWhile isSpace str) of
+        Just ('#',rest) -> case B8.stripPrefix "niv:" (B8.dropWhile isSpace rest) of
+          Just rest' -> case B8.stripPrefix "no_update" (B8.dropWhile isSpace rest') of
+            Just{} -> True
             _ -> False
           _ -> False
         _ -> False
 
 warnIfOutdated :: IO ()
 warnIfOutdated = do
-    tryAny (readFile pathNixSourcesNix) >>= \case
+    tryAny (B.readFile pathNixSourcesNix) >>= \case
       Left e -> putStrLn $ unlines
         [ "Could not read " <> pathNixSourcesNix
         , "Error: " <> show e
@@ -650,51 +653,15 @@ pathNixSourcesNix :: FilePath
 pathNixSourcesNix = "nix" </> "sources.nix"
 
 -- | Glue code between nix and sources.json
-initNixSourcesNixContent :: String
-initNixSourcesNixContent = [s|
-# This file has been generated by Niv.
-
-# A record, from name to path, of the third-party packages
-with rec
-{
-  pkgs = import <nixpkgs> {};
-
-  sources = builtins.fromJSON (builtins.readFile ./sources.json);
-
-  mapAttrs = builtins.mapAttrs or
-    (f: set: with builtins;
-      listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
-
-  getFetcher = spec:
-    let fetcherName =
-      if builtins.hasAttr "type" spec
-      then builtins.getAttr "type" spec
-      else "tarball";
-    in builtins.getAttr fetcherName {
-      "tarball" = pkgs.fetchzip;
-      "file" = pkgs.fetchurl;
-    };
-};
-# NOTE: spec must _not_ have an "outPath" attribute
-mapAttrs (_: spec:
-  if builtins.hasAttr "outPath" spec
-  then abort
-    "The values in sources.json should not have an 'outPath' attribute"
-  else
-    if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
-    then
-      spec //
-      { outPath = getFetcher spec { inherit (spec) url sha256; } ; }
-    else spec
-  ) sources
-|]
+initNixSourcesNixContent :: B.ByteString
+initNixSourcesNixContent = $(embedFile "nix/sources.nix")
 
 -- | @nix/sources.json"
 pathNixSourcesJson :: FilePath
 pathNixSourcesJson = "nix" </> "sources.json"
 
 -- | Empty JSON map
-initNixSourcesJsonContent :: String
+initNixSourcesJsonContent :: B.ByteString
 initNixSourcesJsonContent = "{}"
 
 -------------------------------------------------------------------------------
diff --git a/default.nix b/default.nix
index 0b22727..2c46a64 100644
--- a/default.nix
+++ b/default.nix
@@ -4,6 +4,8 @@ with rec
     [ "^package.yaml$"
       "^app.*$"
       "^README.md$"
+      "^nix$"
+      "^nix.sources.nix$"
     ];
   haskellPackages = pkgs.haskellPackages.override
     { overrides = _: haskellPackages:
diff --git a/package.yaml b/package.yaml
index 9ec6318..3a7c28b 100644
--- a/package.yaml
+++ b/package.yaml
@@ -11,6 +11,7 @@ executable:
     dependencies:
         - base
         - hashable
+        - file-embed
         - process
         - text
         - bytestring
@@ -24,3 +25,5 @@ executable:
         - optparse-applicative
         - unliftio
         - unordered-containers
+    data-files:
+        - nix/sources.nix