diff --git a/default.nix b/default.nix
index c97e9c9..5377e57 100644
--- a/default.nix
+++ b/default.nix
@@ -1,13 +1,44 @@
-{ pkgs ? import (import ./npins).nixpkgs {} }:
 {
-  production = pkgs.buildNpmPackage {
+  sources ? import ./npins,
+  pkgs ? import sources.nixpkgs { },
+}:
+
+let
+  inherit (pkgs.lib.fileset)
+    fileFilter
+    gitTrackedWith
+    intersection
+    toSource
+    ;
+in
+
+{
+  package = pkgs.buildNpmPackage {
     name = "metis";
-    src = ./.;
+
+    src = toSource {
+      root = ./.;
+      fileset = intersection (gitTrackedWith { } ./.) (
+        fileFilter ({ name, hasExt, ... }: !(hasExt "nix") && name != "npins") ./.
+      );
+    };
+
     npmDepsHash = "sha256-RbjWNVY8KlPP9ajQRnrsWhOZiiyyMGQSY39lmZnTC1I=";
+
     installPhase = ''
       cp -r public $out
-      '';
+    '';
+  };
+
+  devShell = pkgs.mkShell {
+    name = "metis.dev";
+
+    packages = [ pkgs.nodejs ];
+  };
+
+  providers = {
+    eleves-ens = "cloud.eleves.ens.fr";
+    frama-agenda = "framagenda.org";
+    dgnum-nc = "cloud.dgnum.eu";
   };
-  shell = import ./shell.nix { inherit pkgs; };
-  providers = import ./providers.nix;
 }
diff --git a/providers.nix b/providers.nix
deleted file mode 100644
index 52acbd5..0000000
--- a/providers.nix
+++ /dev/null
@@ -1,8 +0,0 @@
-let
-  providers = {
-    eleves-ens = "cloud.eleves.ens.fr";
-    frama-agenda = "framagenda.org";
-    dgnum-nc = "cloud.dgnum.eu";
-  };
-in
-  builtins.mapAttrs (name: value: "https://${value}/remote.php/dav/public-calendars/") providers
diff --git a/shell.nix b/shell.nix
index 8fffe07..d6d21cf 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,4 +1 @@
-{ pkgs ? import (import ./npins).nixpkgs {} }:
-pkgs.mkShell {
-  packages = [ pkgs.nodejs ];
-}
+(import ./. { }).devShell