diff --git a/nix/modules/darwin/nix/default.nix b/nix/modules/darwin/nix/default.nix
index 789805a..5ad62ee 100644
--- a/nix/modules/darwin/nix/default.nix
+++ b/nix/modules/darwin/nix/default.nix
@@ -20,6 +20,7 @@ in {
       nixfmt
       nix-index
       nix-prefetch-git
+      nvd
     ];
 
     nix = let
@@ -68,5 +69,14 @@ in {
       generateNixPathFromInputs = true;
       linkInputs = true;
     };
+    system.activationScripts.postUserActivation =
+      {
+        text = ''
+          ${pkgs.nvd}/bin/nvd --nix-bin-dir=${pkgs.nix}/bin diff /run/current-system "$systemConfig"
+        '';
+      }
+      // lib.optionalAttrs pkgs.stdenv.isLinux {
+        supportsDryActivation = true;
+      };
   };
 }
diff --git a/nix/modules/nixos/system/nix/default.nix b/nix/modules/nixos/system/nix/default.nix
index 33ae4fe..9619c45 100644
--- a/nix/modules/nixos/system/nix/default.nix
+++ b/nix/modules/nixos/system/nix/default.nix
@@ -26,6 +26,7 @@ in {
       nixfmt
       nix-index
       nix-prefetch-git
+      nvd
     ];
 
     nix = let
@@ -65,5 +66,11 @@ in {
       generateNixPathFromInputs = true;
       linkInputs = true;
     };
+    system.activationScripts.diff = {
+      supportsDryActivation = true;
+      text = ''
+        ${pkgs.nvd}/bin/nvd --nix-bin-dir=${pkgs.nix}/bin diff /run/current-system "$systemConfig"
+      '';
+    };
   };
 }