diff --git a/default.nix b/default.nix
index b052317..1178d04 100644
--- a/default.nix
+++ b/default.nix
@@ -1,6 +1,6 @@
 { stdenv
 , lib
-, nixUnstable
+, nix
 , meson
 , cmake
 , ninja
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   src = if srcDir == null then filterMesonBuild ./. else srcDir;
   buildInputs = [
     nlohmann_json
-    nixUnstable
+    nix
     boost
   ];
   nativeBuildInputs = [
diff --git a/flake.lock b/flake.lock
index 6063da8..3f2e2f5 100644
--- a/flake.lock
+++ b/flake.lock
@@ -2,11 +2,11 @@
   "nodes": {
     "flake-utils": {
       "locked": {
-        "lastModified": 1637014545,
-        "narHash": "sha256-26IZAc5yzlD9FlDT54io1oqG/bBoyka+FJk5guaX4x4=",
+        "lastModified": 1638122382,
+        "narHash": "sha256-sQzZzAbvKEqN9s0bzWuYmRaA03v40gaJ4+iL1LXjaeI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "bba5dcc8e0b20ab664967ad83d24d64cb64ec4f4",
+        "rev": "74f7e4319258e287b0f9cb95426c9853b282730b",
         "type": "github"
       },
       "original": {
@@ -17,11 +17,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1639573498,
-        "narHash": "sha256-YAoywqjyjOJYuEZpA8sln84jk99GG9hYbPEYXwGEGGM=",
+        "lastModified": 1641577433,
+        "narHash": "sha256-T7lS8vpbC3dgtrkb2ueC9HWaX4RYUwdP7IEttnvKQ8Y=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "aef12c8678fd5e927edba764bd04f3ba2930ae15",
+        "rev": "568e0bc498ee51fdd88e1e94089de05f2fdbd18b",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 6e4dd50..963055a 100644
--- a/flake.nix
+++ b/flake.nix
@@ -13,31 +13,38 @@
       rec {
         packages.nix-eval-jobs = pkgs.callPackage ./default.nix drvArgs;
 
-        checks = {
+        checks =
+          let
+            mkVariant = nix: packages.nix-eval-jobs.overrideAttrs (_: {
+              name = "nix-eval-jobs-${nix.version}";
+              inherit (nix) version;
+            });
+          in
+          {
 
-          editorconfig = pkgs.runCommand "editorconfig-check"
-            {
-              nativeBuildInputs = [
-                pkgs.editorconfig-checker
-              ];
-            } ''
-            editorconfig-checker ${self}
-            touch $out
-          '';
+            editorconfig = pkgs.runCommand "editorconfig-check"
+              {
+                nativeBuildInputs = [
+                  pkgs.editorconfig-checker
+                ];
+              } ''
+              editorconfig-checker ${self}
+              touch $out
+            '';
 
-          nixpkgs-fmt = pkgs.runCommand "fmt-check"
-            {
-              nativeBuildInputs = [
-                pkgs.nixpkgs-fmt
-              ];
-            } ''
-            nixpkgs-fmt --check .
-            touch $out
-          '';
+            nixpkgs-fmt = pkgs.runCommand "fmt-check"
+              {
+                nativeBuildInputs = [
+                  pkgs.nixpkgs-fmt
+                ];
+              } ''
+              nixpkgs-fmt --check .
+              touch $out
+            '';
 
-          build = packages.nix-eval-jobs;
-
-        };
+            build = mkVariant pkgs.nix;
+            build-unstable = mkVariant pkgs.nixUnstable;
+          };
 
         defaultPackage = self.packages.${system}.nix-eval-jobs;
         devShell = pkgs.callPackage ./shell.nix drvArgs;
diff --git a/shell.nix b/shell.nix
index 7b97e75..70b4e37 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,8 +1,22 @@
-{ pkgs ? import <nixpkgs> { }
+{ pkgs ? (
+    let
+      inherit (builtins) fromJSON readFile;
+      flakeLock = fromJSON (readFile ./flake.lock);
+      locked = flakeLock.nodes.nixpkgs.locked;
+      nixpkgs = assert locked.type == "github"; builtins.fetchTarball {
+        url = "https://github.com/${locked.owner}/${locked.repo}/archive/${locked.rev}.tar.gz";
+        sha256 = locked.narHash;
+      };
+    in
+    import nixpkgs { }
+  )
 , srcDir ? null
 }:
 
-(pkgs.callPackage ./default.nix { inherit srcDir; }).overrideAttrs (old: {
+(pkgs.callPackage ./default.nix {
+  inherit srcDir;
+  nix = pkgs.nixUnstable;
+}).overrideAttrs (old: {
 
   nativeBuildInputs = old.nativeBuildInputs ++ [