diff --git a/Main.hs b/Main.hs
index c35fcb5..69c2233 100644
--- a/Main.hs
+++ b/Main.hs
@@ -569,35 +569,37 @@ pathNixSourcesNix :: FilePath
 pathNixSourcesNix = "nix" </> "sources.nix"
 
 -- | Glue code between nix and sources.json
--- TODO: update this
 initNixSourcesNixContent :: String
 initNixSourcesNixContent = [s|
 # A record, from name to path, of the third-party packages
 with
 {
-  versions = builtins.fromJSON (builtins.readFile ./sources.json);
+  sources = builtins.fromJSON (builtins.readFile ./sources.json);
 
-  # fetchTarball version that is compatible between all the versions of Nix
+  # fetchTarball version that is compatible between all the sources of Nix
   fetchTarball =
     { url, sha256 }:
       if builtins.lessThan builtins.nixVersion "1.12" then
         builtins.fetchTarball { inherit url; }
       else
         builtins.fetchTarball { inherit url sha256; };
+  mapAttrs = builtins.mapAttrs or
+    (f: set: with builtins;
+      listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
 };
 
 # NOTE: spec must _not_ have an "outPath" attribute
-builtins.mapAttrs (_: spec:
+mapAttrs (_: spec:
   if builtins.hasAttr "outPath" spec
   then abort
-    "The values in versions.json should not have an 'outPath' attribute"
+    "The values in sources.json should not have an 'outPath' attribute"
   else
     if builtins.hasAttr "url" spec && builtins.hasAttr "sha256" spec
     then
       spec //
     { outPath = fetchTarball { inherit (spec) url sha256; } ; }
     else spec
-  ) versions
+  ) sources
 |]
 
 -- | @nix/default.nix@