diff --git a/default.nix b/default.nix
index 1fe3a98..642c84a 100644
--- a/default.nix
+++ b/default.nix
@@ -1,3 +1,6 @@
-{ pkgs ? import <nixpkgs> {} }:
+{ }:
 
-pkgs.callPackage ./site.nix {}
+let
+  sources = import ./nix/sources.nix;
+  pkgs = import sources.nixpkgs { };
+in pkgs.callPackage ./site.nix { pkgs = pkgs; }
diff --git a/nix/sources.json b/nix/sources.json
index 225728a..b939bc2 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -1,4 +1,28 @@
 {
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv",
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "2ecfd86b631714b457e56d70dd83fa60435baeb6",
+        "sha256": "01j6727cws8blg1npp54b4w6xa0gpgyzhyws2vqgp8clnlnmqqhi",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/2ecfd86b631714b457e56d70dd83fa60435baeb6.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "master",
+        "description": "Nix Packages collection",
+        "homepage": null,
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "48704fbd4fc4dc9660ab04f938048b4894ecb140",
+        "sha256": "1yghh74jw93air3jwljiyl79iypl9rgr4x4aag0f2jyq73vhzf8p",
+        "type": "tarball",
+        "url": "https://github.com/NixOS/nixpkgs/archive/48704fbd4fc4dc9660ab04f938048b4894ecb140.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "vgo2nix": {
         "branch": "master",
         "description": null,
diff --git a/shell.nix b/shell.nix
index fd893ee..1626e5b 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,6 +1,6 @@
 let
-  pkgs = import <nixpkgs> { };
   sources = import ./nix/sources.nix;
+  pkgs = import sources.nixpkgs { };
   xepkgs = import sources.xepkgs { };
   vgo2nix = import sources.vgo2nix { };
 in pkgs.mkShell { buildInputs = [ pkgs.go pkgs.niv xepkgs.gopls vgo2nix ]; }