diff --git a/system/nixos-installer.nix b/system/nixos-installer.nix
new file mode 100644
index 00000000000..285b3043c30
--- /dev/null
+++ b/system/nixos-installer.nix
@@ -0,0 +1,98 @@
+{pkgs, config, ...}:
+
+###### interface
+let
+  inherit (pkgs.lib) mkOption mkIf;
+
+  options = {
+    installer = {
+      nixpkgsURL = mkOption {
+        default = "";
+        example = http://nixos.org/releases/nix/nixpkgs-0.11pre7577;
+        description = "
+          URL of the Nixpkgs distribution to use when building the
+          installation CD.
+        ";
+      };
+
+      repos = {
+        nixos = mkOption {
+          default = [ { type  = "svn"; }  ];
+          example = [ { type = "svn"; url = "https://svn.nixos.org/repos/nix/nixos/branches/stdenv-updates"; target = "/etc/nixos/nixos-stdenv-updates"; }
+                      { type = "git"; initialize = ''git clone git://mawercer.de/nixos $target''; update = "git pull origin"; target = "/etc/nixos/nixos-git"; }
+                    ];
+          description = ''
+            The NixOS repository from which the system will be built.
+            <command>nixos-checkout</command> will update all working
+            copies of the given repositories,
+            <command>nixos-rebuild</command> will use the first item
+            which has the attribute <literal>default = true</literal>
+            falling back to the first item. The type defines the
+            repository tool added to the path. It also defines a "valid"
+            repository.  If the target directory already exists and it's
+            not valid it will be moved to the backup location
+            <filename><replaceable>dir</replaceable>-date</filename>.
+            For svn the default target and repositories are
+            <filename>/etc/nixos/nixos</filename> and
+            <filename>https://svn.nixos.org/repos/nix/nixos/trunk</filename>.
+            For git repositories update is called after initialization
+            when the repo is initialized.  The initialize code is run
+            from working directory dirname
+            <replaceable>target</replaceable> and should create the
+            directory
+            <filename><replaceable>dir</replaceable></filename>. (<command>git
+            clone url nixos/nixpkgs/services</command> should do) For
+            the executables used see <option>repoTypes</option>.
+          '';
+        };
+
+        nixpkgs = mkOption {
+          default = [ { type  = "svn"; }  ];
+          description = "same as <option>repos.nixos</option>";
+        };
+
+        services = mkOption {
+          default = [ { type  = "svn"; } ];
+          description = "same as <option>repos.nixos</option>";
+        };
+      };
+
+      repoTypes = mkOption {
+        default = {
+          svn = { valid = "[ -d .svn ]"; env = [ pkgs.coreutils pkgs.subversion ]; };
+          git = { valid = "[ -d .git ]"; env = [ pkgs.coreutils pkgs.git pkgs.gnused /*  FIXME: use full path to sed in nix-pull */ ]; };
+        };
+        description = ''
+          Defines, for each supported version control system
+          (e.g. <literal>git</literal>), the dependencies for the
+          mechanism, as well as a test used to determine whether a
+          directory is a checkout created by that version control
+          system.
+        '';
+      };
+
+      manifests = mkOption {
+        default = [http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/MANIFEST];
+        example =
+          [ http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/MANIFEST
+            http://nixos.org/releases/nixpkgs/channels/nixpkgs-stable/MANIFEST
+          ];
+        description = "
+          URLs of manifests to be downloaded when you run
+          <command>nixos-rebuild</command> to speed up builds.
+        ";
+      };
+    };
+  };
+
+
+in
+
+###### implementation
+
+mkIf config.services.pulseaudio.enable {
+  require = [
+    options
+  ];
+
+}
diff --git a/system/options.nix b/system/options.nix
index df484d47451..4cff3ac9296 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -1697,88 +1697,6 @@ in
 
   };
 
-  installer = {
-
-    nixpkgsURL = mkOption {
-      default = "";
-      example = http://nixos.org/releases/nix/nixpkgs-0.11pre7577;
-      description = "
-        URL of the Nixpkgs distribution to use when building the
-        installation CD.
-      ";
-    };
-
-    repos = {
-      nixos = mkOption {
-        default = [ { type  = "svn"; }  ];
-        example = [ { type = "svn"; url = "https://svn.nixos.org/repos/nix/nixos/branches/stdenv-updates"; target = "/etc/nixos/nixos-stdenv-updates"; }
-                    { type = "git"; initialize = ''git clone git://mawercer.de/nixos $target''; update = "git pull origin"; target = "/etc/nixos/nixos-git"; }
-                  ];
-        description = ''
-          The NixOS repository from which the system will be built.
-          <command>nixos-checkout</command> will update all working
-          copies of the given repositories,
-          <command>nixos-rebuild</command> will use the first item
-          which has the attribute <literal>default = true</literal>
-          falling back to the first item. The type defines the
-          repository tool added to the path. It also defines a "valid"
-          repository.  If the target directory already exists and it's
-          not valid it will be moved to the backup location
-          <filename><replaceable>dir</replaceable>-date</filename>.
-          For svn the default target and repositories are
-          <filename>/etc/nixos/nixos</filename> and
-          <filename>https://svn.nixos.org/repos/nix/nixos/trunk</filename>.
-          For git repositories update is called after initialization
-          when the repo is initialized.  The initialize code is run
-          from working directory dirname
-          <replaceable>target</replaceable> and should create the
-          directory
-          <filename><replaceable>dir</replaceable></filename>. (<command>git
-          clone url nixos/nixpkgs/services</command> should do) For
-          the executables used see <option>repoTypes</option>.
-        '';
-      };
-
-      nixpkgs = mkOption {
-        default = [ { type  = "svn"; }  ];
-        description = "same as <option>repos.nixos</option>";
-      };
-
-      services = mkOption {
-        default = [ { type  = "svn"; } ];
-        description = "same as <option>repos.nixos</option>";
-      };
-    };
-
-    repoTypes = mkOption {
-      default = {
-        svn = { valid = "[ -d .svn ]"; env = [ pkgs.coreutils pkgs.subversion ]; };
-        git = { valid = "[ -d .git ]"; env = [ pkgs.coreutils pkgs.git pkgs.gnused /*  FIXME: use full path to sed in nix-pull */ ]; };
-      };
-      description = ''
-        Defines, for each supported version control system
-        (e.g. <literal>git</literal>), the dependencies for the
-        mechanism, as well as a test used to determine whether a
-        directory is a checkout created by that version control
-        system.
-      '';
-    };
-
-    manifests = mkOption {
-      default = [http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/MANIFEST];
-      example =
-        [ http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable/MANIFEST
-          http://nixos.org/releases/nixpkgs/channels/nixpkgs-stable/MANIFEST
-        ];
-      description = "
-        URLs of manifests to be downloaded when you run
-        <command>nixos-rebuild</command> to speed up builds.
-      ";
-    };
-
-  };
-
-
   nesting = {
     children = mkOption {
       default = [];
@@ -1859,6 +1777,7 @@ in
     (import ../upstart-jobs/gw6c.nix) # Gateway6
 
     (import ../upstart-jobs/nix.nix) # nix options and daemon
+    (import ../system/nixos-installer.nix)
 
 
     #users