diff --git a/upstart-jobs/xserver/desktopManager/default.nix b/upstart-jobs/xserver/desktopManager/default.nix
index 7ea495716984..f03553812333 100644
--- a/upstart-jobs/xserver/desktopManager/default.nix
+++ b/upstart-jobs/xserver/desktopManager/default.nix
@@ -57,12 +57,12 @@ in
           description = "
             Default desktop manager loaded if none have been chosen.
           ";
-          merge = list:
-            let defaultDM = mergeOneOption list; in
+          merge = mergeOneOption;
+          apply = defaultDM:
             if any (w: w.name == defaultDM) cfg.session.list then
               defaultDM
             else
-              throw "Default desktop manager not found.";
+              throw "Default desktop manager ($(defaultDM)) not found.";
         };
       };
     };
diff --git a/upstart-jobs/xserver/desktopManager/xterm.nix b/upstart-jobs/xserver/desktopManager/xterm.nix
index e8aa0d289cb7..7066c44527cb 100644
--- a/upstart-jobs/xserver/desktopManager/xterm.nix
+++ b/upstart-jobs/xserver/desktopManager/xterm.nix
@@ -8,8 +8,8 @@ let
 
     xterm = {
       enable = mkOption {
-        default = false;
-        example = true;
+        default = true;
+        example = false;
         description = "Enable a xterm terminal as a desktop manager.";
       };
     };
diff --git a/upstart-jobs/xserver/windowManager/default.nix b/upstart-jobs/xserver/windowManager/default.nix
index cb5a1b674e04..5e33b58b3b11 100644
--- a/upstart-jobs/xserver/windowManager/default.nix
+++ b/upstart-jobs/xserver/windowManager/default.nix
@@ -45,12 +45,12 @@ in
           description = "
             Default window manager loaded if none have been chosen.
           ";
-          merge = list:
-            let defaultWM = mergeOneOption list; in
+          merge = mergeOneOption;
+          apply = defaultWM:
             if any (w: w.name == defaultWM) cfg.session then
               defaultWM
             else
-              throw "Default window manager not found.";
+              throw "Default window manager (${defaultWM}) not found.";
         };
       };
     };