diff --git a/modules/legacy.nix b/modules/legacy.nix
index 8b4d7199ae0..6359682f17c 100644
--- a/modules/legacy.nix
+++ b/modules/legacy.nix
@@ -3,7 +3,6 @@
     ../system/assertion.nix
     ../system/nixos-environment.nix
     ../system/nixos-installer.nix
-    ../system/system-options.nix
     ../upstart-jobs/cron/locate.nix
     ../upstart-jobs/filesystems.nix
     ../upstart-jobs/guest-users.nix
diff --git a/modules/system/activation/top-level.nix b/modules/system/activation/top-level.nix
index 306037d1f57..d09f34264e9 100644
--- a/modules/system/activation/top-level.nix
+++ b/modules/system/activation/top-level.nix
@@ -2,6 +2,25 @@
 
 let
 
+  options = {
+  
+    system.build = pkgs.lib.mkOption {
+      default = {};
+      description = ''
+        Attribute set of derivations used to setup the system.
+      '';
+    };
+
+    nesting.children = pkgs.lib.mkOption {
+      default = [];
+      description = ''
+        Additional configurations to build.
+      '';
+    };
+    
+  };
+
+    
   # This attribute is responsible for creating boot entries for 
   # child configuration. They are only (directly) accessible
   # when the parent configuration is boot default. For example,
@@ -77,7 +96,7 @@ let
 
 
 in {
+  require = [options];
 
   system.build.system = system;
-
 }
diff --git a/system/options.nix b/system/options.nix
index eb51250d28e..8c725255487 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -80,15 +80,5 @@ in
   };
 
 
-  nesting = {
-    children = mkOption {
-      default = [];
-      description = "
-        Additional configurations to build.
-      ";
-    };
-  };
-
-  
   require = import ../modules/module-list.nix;
 }
diff --git a/system/system-options.nix b/system/system-options.nix
deleted file mode 100644
index 25bc58b5704..00000000000
--- a/system/system-options.nix
+++ /dev/null
@@ -1,30 +0,0 @@
-# this file contains all extendable options originally defined in system.nix
-# TODO: split it to make it readable.
-{pkgs, config, ...}:
-
-with pkgs.lib;
-
-###### interface
-let
-
-  option = {
-    system = {
-      build = mkOption {
-        default = {};
-        description = ''
-          Attribute set of derivations used to setup the system.
-        '';
-      };
-    };
-  };
-in
-
-###### implementation
-{
-  require = [
-    option
-
-    # config.system.activationScripts
-    # ../system/activate-configuration.nix
-  ];
-}