Enable upower's systemd unit

modules/misc/nixpkgs.nix

@@ -78,6 +78,8 @@ in
       #udev = pkgs.systemd;
       slim = pkgs.slim.override { consolekit = null; };
       lvm2 = pkgs.lvm2.override { udev = pkgs.systemd; };
+      upower = pkgs.upower.override { useSystemd = true; };
+      polkit = pkgs.polkit.override { useSystemd = true; };
     };
 
   };

modules/services/hardware/upower.nix

@@ -35,6 +35,8 @@ with pkgs.lib;
 
     services.udev.packages = [ pkgs.upower ];
 
+    boot.systemd.packages = [ pkgs.upower ];
+
     system.activationScripts.upower =
       ''
         mkdir -m 0755 -p /var/lib/upower