diff --git a/nix/home-manager/profiles/common.nix b/nix/home-manager/profiles/common.nix
index bcc1d27..1f6ffc0 100644
--- a/nix/home-manager/profiles/common.nix
+++ b/nix/home-manager/profiles/common.nix
@@ -25,9 +25,6 @@ in {
       dropbearStatic = dropbear.override {
         enableStatic = true;
       };
-
-      just = pkgs.callPackage ../../pkgs/just.nix {};
-      duplicacy = pkgs.callPackage ../../pkgs/duplicacy {};
     };
   };
 
diff --git a/nix/os/devices/CFB4ED74/pkg.nix b/nix/os/devices/CFB4ED74/pkg.nix
index bf70991..277d01a 100644
--- a/nix/os/devices/CFB4ED74/pkg.nix
+++ b/nix/os/devices/CFB4ED74/pkg.nix
@@ -13,7 +13,7 @@
   };
 
  services.hydra = {
-    enable = true;
+    enable = false;
     hydraURL = "http://localhost:3000"; # externally visible URL
     notificationSender = "hydra@${config.networking.hostName}.stefanjunker.de"; # e-mail of hydra service
     # a standalone hydra will require you to unset the buildMachinesFiles list to avoid using a nonexistant /etc/nix/machines
diff --git a/nix/os/devices/steveej-t480s-work/system.nix b/nix/os/devices/steveej-t480s-work/system.nix
index e974b08..c280844 100644
--- a/nix/os/devices/steveej-t480s-work/system.nix
+++ b/nix/os/devices/steveej-t480s-work/system.nix
@@ -5,7 +5,6 @@
 
 let
   keys = import ../../../variables/keys.nix;
-  mfcl3770cdw = pkgs.callPackage ../../../pkgs/mfcl3770cdw.nix {};
 in {
 
   # TASK: new device
diff --git a/nix/os/profiles/common/configuration.nix b/nix/os/profiles/common/configuration.nix
index 0540f85..63c44de 100644
--- a/nix/os/profiles/common/configuration.nix
+++ b/nix/os/profiles/common/configuration.nix
@@ -1,6 +1,10 @@
 { ... }:
 
 {
+  nixpkgs.overlays = [
+     (import ../../../overlay.nix)
+  ];
+
   imports = [ 
     ./boot.nix
     ./pkg.nix
diff --git a/nix/overlay.nix b/nix/overlay.nix
new file mode 100644
index 0000000..1d13c4f
--- /dev/null
+++ b/nix/overlay.nix
@@ -0,0 +1,5 @@
+self: super: {
+  duplicay = super.callPackage ./pkgs/duplicacy {};
+  mfcl3770cdw = super.callPackage ./pkgs/mfcl3770cdw.nix {};
+  just = super.callPackage ./pkgs/just.nix {};
+}
diff --git a/shell.nix b/shell.nix
index d83e92f..999eba0 100644
--- a/shell.nix
+++ b/shell.nix
@@ -2,7 +2,7 @@
 
 let
   channels-nixos-stable-path = (builtins.fetchTarball https://github.com/NixOS/nixpkgs-channels/archive/7e88992a8c7b2de0bcb89182d8686b27bd93e46a.tar.gz);
-  channels-nixos-stable = import channels-nixos-stable-path {};
+  channels-nixos-stable = import channels-nixos-stable-path { overlays = [ (import ./nix/overlay.nix) ]; };
 
 in
 with channels-nixos-stable;
@@ -10,7 +10,7 @@ stdenv.mkDerivation {
   name = "infra-env";
   buildInputs = [
     (with import (channels-nixos-stable-path+"/nixos") { configuration = {}; }; with config.system.build; [ nixos-generate-config nixos-install nixos-enter manual.manpages ])
-    (pkgs.callPackage ./nix/pkgs/just.nix {})
+    just
     git-crypt
     vcsh
     gnupg