diff --git a/default.nix b/default.nix
index b5f0cd15d..1ce8e5977 100644
--- a/default.nix
+++ b/default.nix
@@ -3,7 +3,15 @@
 , compiler ? "ghc948"
 
 , # Commit of the Nixpkgs repository that we want to use.
-  nixpkgsVersion ? import nix/nixpkgs-version.nix
+  # It defaults to reading the inputs from flake.lock, which serves
+  # as a compatibility layer for non-flake builds / default.nix / shell.nix.
+  nixpkgsVersion ? let
+    lock = builtins.fromJSON (builtins.readFile ./flake.lock);
+  in
+  {
+    inherit (lock.nodes.nixpkgs.locked) owner repo rev;
+    tarballHash = lock.nodes.nixpkgs.locked.narHash;
+  }
 
 , # Nix files that describe the Nixpkgs repository. We evaluate the expression
   # using `import` below.
@@ -119,10 +127,6 @@ rec {
   memory =
     pkgs.callPackage nix/tools/memory.nix { inherit postgrestProfiled withTools; };
 
-  # Utility for updating the pinned version of Nixpkgs.
-  nixpkgsTools =
-    pkgs.callPackage nix/tools/nixpkgsTools.nix { };
-
   # Scripts for publishing new releases.
   release =
     pkgs.callPackage nix/tools/release.nix { };
diff --git a/flake.lock b/flake.lock
index ba0150abf..9994726e2 100644
--- a/flake.lock
+++ b/flake.lock
@@ -1,23 +1,24 @@
 {
   "nodes": {
-    "nixpkgs-lib": {
+    "nixpkgs": {
       "locked": {
-        "lastModified": 1742692082,
-        "narHash": "sha256-s3XOULQj7BVO7myY5V4Sob0tRZ7nRpwEOIzXg/MkD/Q=",
-        "owner": "nix-community",
-        "repo": "nixpkgs.lib",
-        "rev": "a09310bc940f245e51b1ffea68731244ca38f2bd",
+        "lastModified": 1731165248,
+        "narHash": "sha256-DiHFKIdBmMx5/DUARhVqaxvEIiy4EE6Eqs9Qs4oxme8=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "a90280100f41a10914edfe729a4053e60c92b8e3",
         "type": "github"
       },
       "original": {
-        "owner": "nix-community",
-        "repo": "nixpkgs.lib",
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
         "type": "github"
       }
     },
     "root": {
       "inputs": {
-        "nixpkgs-lib": "nixpkgs-lib"
+        "nixpkgs": "nixpkgs"
       }
     }
   },
diff --git a/flake.nix b/flake.nix
index f64c907c2..24f4c50f2 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,7 +2,7 @@
   description = "REST API for any Postgres database";
 
   inputs = {
-    nixpkgs-lib.url = "github:nix-community/nixpkgs.lib";
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
   };
 
   nixConfig = {
@@ -10,7 +10,7 @@
     extra-trusted-public-keys = "postgrest.cachix.org-1:icgW4R15fz1+LqvhPjt4EnX/r19AaqxiVV+1olwlZtI=";
   };
 
-  outputs = { nixpkgs-lib, ... }:
+  outputs = { nixpkgs, ... }:
     let
       systems = [
         "aarch64-darwin"
@@ -21,15 +21,21 @@
 
       pgrstFor = system: import ./default.nix {
         inherit system;
+        nixpkgsVersion = {
+          owner = "nixos";
+          repo = "nixpkgs";
+          inherit (nixpkgs) rev;
+          tarballHash = nixpkgs.narHash;
+        };
       };
 
-      genSystems = f: nixpkgs-lib.lib.genAttrs systems (system: f (pgrstFor system));
+      genSystems = f: nixpkgs.lib.genAttrs systems (system: f (pgrstFor system));
     in
     {
       packages = genSystems (attrs: {
         default = attrs.postgrestPackage;
         profiled = attrs.postgrestProfiled;
-      } // nixpkgs-lib.lib.optionalAttrs (attrs ? postgrestStatic) {
+      } // nixpkgs.lib.optionalAttrs (attrs ? postgrestStatic) {
         static = attrs.postgrestStatic;
       });
 
diff --git a/nix/README.md b/nix/README.md
index c138a3cb0..9b5798d10 100644
--- a/nix/README.md
+++ b/nix/README.md
@@ -379,10 +379,8 @@ that).
 
 We also use `default.nix` to load our pinned version of the `nixpkgs`
 repository. This set of packages will always be the same, independently from
-where or when you use it. The pinned version can be upgraded with the small
-`nixpkgs-upgrade` utility. Running `nixpkgs-upgrade > nix/nixpkgs-version.nix`
-in `nix-shell` will upgrade the pinned version to the latest `nixpkgs-unstable`
-version.
+where or when you use it. The pinned version is taken from `flake.lock` and
+can be updated with `nix flake update`.
 
 ### `shell.nix`
 
diff --git a/nix/nixpkgs-version.nix b/nix/nixpkgs-version.nix
deleted file mode 100644
index 52dcfe645..000000000
--- a/nix/nixpkgs-version.nix
+++ /dev/null
@@ -1,9 +0,0 @@
-# Pinned version of Nixpkgs, generated with postgrest-nixpkgs-upgrade.
-{
-  owner = "NixOS";
-  repo = "nixpkgs";
-  ref = "refs/heads/nixpkgs-unstable-darwin";
-  date = "2024-11-09";
-  rev = "a90280100f41a10914edfe729a4053e60c92b8e3";
-  tarballHash = "1vwr665b6l6gma24w45q5hic86vbd8alc01mziwwr621hwlca88f";
-}
diff --git a/nix/tools/nixpkgsTools.nix b/nix/tools/nixpkgsTools.nix
deleted file mode 100644
index 6ae8234a0..000000000
--- a/nix/tools/nixpkgsTools.nix
+++ /dev/null
@@ -1,62 +0,0 @@
-{ buildToolbox
-, checkedShellScript
-, coreutils
-, curl
-, jq
-, nix
-}:
-# Utility script for pinning the latest stable version of Nixpkgs.
-
-# Instead of pinning Nixpkgs based on the huge Git repository, we reference a
-# specific tarball that only contains the source of the revision that we want
-# to pin.
-let
-  name =
-    "postgrest-nixpkgs-upgrade";
-
-  refUrl =
-    "https://api.github.com/repos/nixos/nixpkgs/git/matching-refs/heads/nixpkgs-";
-
-  githubV3Header =
-    "Accept: application/vnd.github.v3+json";
-
-  tarballUrlBase =
-    "https://github.com/nixos/nixpkgs/archive/";
-
-  upgrade =
-    checkedShellScript
-      {
-        inherit name;
-        docs = "Pin the newest stable version of Nixpkgs.";
-        workingDir = "/";
-      }
-      ''
-        # The list of refs is sorted. The first result will be nixpkgs-unstable, the second the latest stable branch.
-        # shellcheck disable=SC2207
-        commit=($(${curl}/bin/curl "${refUrl}" -H "${githubV3Header}" | ${jq}/bin/jq -r 'sort_by(.ref) | reverse | [.[0].object.sha, .[0].ref] | @tsv'))
-        tarballUrl="${tarballUrlBase}''${commit[0]}.tar.gz"
-        tarballHash="$(${nix}/bin/nix-prefetch-url --unpack "$tarballUrl")"
-        currentDate="$(${coreutils}/bin/date --iso)"
-
-        cat > nix/nixpkgs-version.nix << EOF
-        # Pinned version of Nixpkgs, generated with ${name}.
-        {
-          owner = "NixOS";
-          repo = "nixpkgs";
-          ref = "''${commit[1]}";
-          date = "$currentDate";
-          rev = "''${commit[0]}";
-          tarballHash = "$tarballHash";
-        }
-        EOF
-
-        echo "# This file is auto-generated by ${name}" > docs/requirements.txt
-        cat "$(nix-build -A docs.requirements)" >> docs/requirements.txt
-      '';
-
-in
-buildToolbox
-{
-  name = "postgrest-nixpkgs";
-  tools = { inherit upgrade; };
-}
diff --git a/shell.nix b/shell.nix
index 12c4e3fe9..854d3b05e 100644
--- a/shell.nix
+++ b/shell.nix
@@ -23,7 +23,6 @@ let
       postgrest.docs
       postgrest.loadtest
       postgrest.memory
-      postgrest.nixpkgsTools
       postgrest.release
       postgrest.style
       postgrest.tests