diff --git a/hosts/server7/default.nix b/hosts/server7/default.nix
index 663db6bf..f741d4fd 100644
--- a/hosts/server7/default.nix
+++ b/hosts/server7/default.nix
@@ -81,9 +81,17 @@ in {
 
   nix = {
     package = pkgs.nixFlakes;
-    extraOptions = "experimental-features = nix-command flakes ca-references";
     gc.automatic = true;
     optimise.automatic = true;
+    extraOptions = ''
+      experimental-features = nix-command flakes ca-references
+      post-build-hook = ${
+        pkgs.writeScript "post-build-sign-paths" ''
+          #!${pkgs.runtimeShell}
+          nix sign-paths --key-file /var/lib/nix-serve.key $OUT_PATHS
+        ''
+      }
+    '';
   };
 
   virtualisation.docker.enable = true;