diff --git a/modules/services/x11/xserver/desktop-managers/kde4.nix b/modules/services/x11/xserver/desktop-managers/kde4.nix
index f8b66e2840d..de0838565fc 100644
--- a/modules/services/x11/xserver/desktop-managers/kde4.nix
+++ b/modules/services/x11/xserver/desktop-managers/kde4.nix
@@ -1,73 +1,70 @@
-{pkgs, config, ...}:
+{ config, pkgs, ... }:
+
+with pkgs.lib;
 
 let
-  inherit (pkgs.lib) mkOption mkIf;
+
   xcfg = config.services.xserver;
   cfg = xcfg.desktopManager.kde4;
   xorg = xcfg.package;
 
-  options = { services = { xserver = { desktopManager = {
-
-    kde4 = {
-      enable = mkOption {
-        default = false;
-        example = true;
-        description = "Enable the kde 4 desktop manager.";
-      };
-    };
-
-  }; }; }; };
 in
 
-mkIf (xcfg.enable && cfg.enable) {
-  require = [
-    options
+{
 
-    # environment.kdePackages
-    ./kde-environment.nix
-  ];
+  imports = [ ./kde-environment.nix ];
 
-  services = {
-    xserver = {
+    
+  options = {
 
-      desktopManager = {
-        session = [{
-          name = "kde4";
-          start = ''
+    services.xserver.desktopManager.kde4.enable = mkOption {
+      default = false;
+      example = true;
+      description = "Enable the KDE 4 desktop environment.";
+    };
+
+  };
+
+  
+  config = mkIf (xcfg.enable && cfg.enable) {
+
+    # If KDE 4 is enabled, make it default desktop manager (unless
+    # overriden by the user's configuration).
+    # !!! doesn't work yet ("Multiple definitions. Only one is allowed
+    # for this option.")
+    # services.xserver.desktopManager.default = mkOverride 900 "kde4";
+
+    services.xserver.desktopManager.session = singleton
+      { name = "kde4";
+        bgSupport = true;
+        start =
+          ''
             # Start KDE.
             exec ${pkgs.kde42.kdebase_workspace}/bin/startkde
           '';
-        }];
       };
 
-    };
-  };
+    security.setuidPrograms = [ "kcheckpass" ];
 
-  security = {
-    extraSetuidPrograms = [
-      "kcheckpass"
-    ];
-  };
+    environment.kdePackages =
+      [ pkgs.kde42.kdelibs
+        pkgs.kde42.kdebase
+        pkgs.kde42.kdebase_runtime
+        pkgs.kde42.kdebase_workspace
+        pkgs.shared_mime_info
+      ];
 
-  environment = {
-    kdePackages = [
-      pkgs.kde42.kdelibs
-      pkgs.kde42.kdebase
-      pkgs.kde42.kdebase_runtime
-      pkgs.kde42.kdebase_workspace
-      pkgs.shared_mime_info
-    ];
+    environment.x11Packages =
+      [ xorg.xmessage # so that startkde can show error messages
+        pkgs.qt4 # needed for qdbus
+        xorg.xset # used by startkde, non-essential
+      ];
 
-    x11Packages = [
-      xorg.xmessage # so that startkde can show error messages
-      pkgs.qt4 # needed for qdbus
-      xorg.xset # used by startkde, non-essential
-    ];
-
-    etc = [
+    environment.etc = singleton
       { source = "${pkgs.xkeyboard_config}/etc/X11/xkb";
         target = "X11/xkb";
-      }
-    ];
+      };
+
   };
+
 }