diff --git a/ci/default.nix b/ci/default.nix
index 5cc5a7b..1994688 100644
--- a/ci/default.nix
+++ b/ci/default.nix
@@ -1,4 +1,4 @@
-{inputs, ...}: {
+{inputs, config, ...}: {
   imports = [
     inputs.hercules-ci-effects.flakeModule
   ];
@@ -16,5 +16,16 @@
       hour = 13;
       dayOfWeek = ["Mon" "Tue" "Wed" "Thu" "Fri" "Sat" "Sun"];
     };
+    pullRequestBody = ''
+      Update `flake.lock`. See the commit message(s) for details.
+      
+      You may reset this branch by deleting it and re-running the update job. xs
+
+          git push origin :${config.hercules-ci.flake-update.updateBranch}
+
+      ```
+      ${builtins.readFile config.packages.x86_64-linux.diff-closures}
+      ```
+    '';
   };
 }
diff --git a/diff-closures/default.nix b/diff-closures/default.nix
index bf7e818..f480a35 100644
--- a/diff-closures/default.nix
+++ b/diff-closures/default.nix
@@ -4,16 +4,34 @@
     self',
     ...
   }: {
-    packages.diff-closures = pkgs.writeShellApplication {
-      name = "diff-closures";
-      runtimeInputs = [pkgs.ansifilter];
-      text = ''
-        nix store diff-closures --derivation \
-          github:aciceri/emacs/master#ccrEmacs \
-          "${inputs.self}#ccrEmacs" \
-        | ansifilter --text
+    packages.diff-closures = let
+      diff-closures-script = pkgs.writeText "diff-closures-script" ''
+	echo ciao
+	export NIX_SSL_CERT_FILE="/etc/ssl/certs/ca-certificates.crt"
+        # nix --extra-experimental-features "nix-command flakes" \
+	#   store diff-closures --derivation \
+        #   github:aciceri/emacs/master#ccrEmacs \
+        #   "${inputs.self}#ccrEmacs" \
+        #   | ${pkgs.ansifilter}/bin/ansifilter --text
+      '';
+    in pkgs.runCommandNoCC
+      "diff-closures"
+      {
+	__impure = true;
+      }
+      ''
+         ${pkgs.bubblewrap}/bin/bwrap \
+	   --dir /run \
+	   --dev /dev \
+	   --bind /build /build \
+	   --bind /proc /proc \
+	   --bind /etc /etc \
+	   --chdir /build \
+	   --setenv PATH "${pkgs.nixVersions.nix_2_14}/bin:${pkgs.busybox}/bin" \
+	   --ro-bind /nix/store /nix/store \
+	   --share-net \
+	   ${pkgs.bash}/bin/bash ${diff-closures-script} > $out  
       '';
-    };
 
     apps.diff-closures.program = "${self'.packages.diff-closures}/bin/diff-closures";
   };