diff --git a/inputs.nix b/inputs.nix
index 9ad7d1e..536a8e9 100644
--- a/inputs.nix
+++ b/inputs.nix
@@ -5,6 +5,10 @@ let self = {
 
 {
   inherit lock;
-  nixpkgs = builtins.fetchTarball "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs}.tar.gz";
+  nixpkgs = builtins.fetchTarball {
+    name = "nixpkgs";
+    url = "https://github.com/NixOS/nixpkgs/archive/${lock.nixpkgs.revision}.tar.gz";
+    sha256 = "${lock.nixpkgs.sha256}";
+  };
 };
 in self
diff --git a/lib/overlays/version-info-fixup.nix b/lib/overlays/version-info-fixup.nix
index 4d4cb9c..b413842 100644
--- a/lib/overlays/version-info-fixup.nix
+++ b/lib/overlays/version-info-fixup.nix
@@ -2,7 +2,7 @@
 
 selfLib: superLib: {
   trivial = superLib.trivial // {
-    versionSuffix = ".git.${builtins.substring 0 12 inputs.lock.nixpkgs}";
-    revisionWithDefault = default: inputs.lock.nixpkgs or default;
+    versionSuffix = ".git.${builtins.substring 0 12 inputs.lock.nixpkgs.revision}";
+    revisionWithDefault = default: inputs.lock.nixpkgs.revision or default;
   };
 }
diff --git a/lock.nix b/lock.nix
index cb24650..d15b646 100644
--- a/lock.nix
+++ b/lock.nix
@@ -1,3 +1,6 @@
 {
-  nixpkgs = "2975732531b5fa6e728f837c6f090335cbef5285" /*git revision*/;
+  nixpkgs = {
+    revision = "2975732531b5fa6e728f837c6f090335cbef5285";
+    sha256 = "0hwawvw8kf70f87ygv9pjndwwiddigh5vv1w5jdbp3dxv9slsx2v";
+  };
 }