diff --git a/system/options.nix b/system/options.nix
index bfad4e37305..2aa64fedd8c 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -906,6 +906,7 @@
           };
 
           notificationSender = mkOption {
+            default = "svn-server@example.org";
             example = "svn-server@example.org";
             description = "
               The email address used in the Sender field of commit
@@ -914,6 +915,7 @@
           };
 
           userCreationDomain = mkOption {
+	    default = "example.org"; 
             example = "example.org";
             description = "
               The domain from which user creation is allowed.  A client can
@@ -931,6 +933,13 @@
               support WebDAV.
             ";
           };
+	  
+	  dataDir = mkOption {
+	    default = "/no/such/path/exists";
+	    description = "
+	      Place to put SVN repository.
+	    ";
+	  };
 
           organization = {
 
@@ -1476,6 +1485,14 @@ root        ALL=(ALL) SETENV: ALL
       ";
     };
 
+    nix = mkOption {
+        default = pkgs: pkgs.nixUnstable;
+        example = pkgs: pkgs.nixCustomFun /root/nix.tar.gz;
+        description = "
+          Use non-default Nix easily. Be careful, though, not to break everything.
+        ";
+    };
+
   };
 
 
diff --git a/system/system.nix b/system/system.nix
index e5d3ca618f7..2745388e0d4 100644
--- a/system/system.nix
+++ b/system/system.nix
@@ -31,7 +31,8 @@ rec {
 
   manifests = config.installer.manifests; # exported here because nixos-rebuild uses it
 
-  nix = pkgs.nixUnstable; # we need the exportReferencesGraph feature
+  /*nix = pkgs.nixUnstable; # we need the exportReferencesGraph feature*/
+  nix = config.environment.nix pkgs;
 
   kernel = config.boot.kernel pkgs;
 
@@ -225,6 +226,7 @@ rec {
     pkgs.utillinux
     pkgs.wirelesstools
     nix
+    (pkgs.lowPrio (pkgs.nixUnstable)) /* Better safe than sorry */
     nixosInstall
     nixosRebuild
     nixosCheckout