diff --git a/nixos/modules/misc/nixpkgs.nix b/nixos/modules/misc/nixpkgs.nix
index 395ba82f2d1..114feb2562d 100644
--- a/nixos/modules/misc/nixpkgs.nix
+++ b/nixos/modules/misc/nixpkgs.nix
@@ -59,8 +59,8 @@ in
     };
 
     nixpkgs.system = mkOption {
-      type = types.str;
-      default = builtins.currentSystem;
+      type = types.uniq types.str;
+      example = "i686-linux";
       description = ''
         Specifies the Nix platform type for which NixOS should be built.
         If unset, it defaults to the platform type of your host system.
diff --git a/nixos/modules/services/misc/nixos-manual.nix b/nixos/modules/services/misc/nixos-manual.nix
index f73c4102cfe..c570a01fb3b 100644
--- a/nixos/modules/services/misc/nixos-manual.nix
+++ b/nixos/modules/services/misc/nixos-manual.nix
@@ -14,6 +14,7 @@ let
   versionModule =
     { system.nixosVersionSuffix = config.system.nixosVersionSuffix;
       system.nixosRevision = config.system.nixosRevision;
+      nixpkgs.system = config.nixpkgs.system;
     };
 
   eval = evalModules {
diff --git a/nixos/modules/services/networking/btsync.nix b/nixos/modules/services/networking/btsync.nix
index 0bfd3b74348..8b90f295ed4 100644
--- a/nixos/modules/services/networking/btsync.nix
+++ b/nixos/modules/services/networking/btsync.nix
@@ -200,7 +200,6 @@ in
 
       package = mkOption {
         type = types.package;
-        default = pkgs.bittorrentSync14;
         example = literalExample "pkgs.bittorrentSync20";
         description = ''
           Branch of bittorrent sync to use.
@@ -277,6 +276,8 @@ in
         }
       ];
 
+    services.btsync.package = mkOptionDefault pkgs.bittorrentSync14;
+
     users.extraUsers.btsync = {
       description     = "Bittorrent Sync Service user";
       home            = cfg.storagePath;