diff --git a/system/options.nix b/system/options.nix
index 6c0322aa70c5..1a2c80f3403b 100644
--- a/system/options.nix
+++ b/system/options.nix
@@ -537,6 +537,17 @@
   }
 
   
+  {
+    name = ["services" "httpd" "subservices" "subversion" "userCreationDomain"];
+    example = "example.org";
+    description = "
+      The domain from which user creation is allowed.  A client can
+      only create a new user account if its IP address resolves to
+      this domain.
+    ";
+  }
+
+  
   {
     name = ["services" "httpd" "subservices" "subversion" "autoVersioning"];
     default = false;
diff --git a/upstart-jobs/httpd.nix b/upstart-jobs/httpd.nix
index e9434d7f0e81..c930dcb3caa0 100644
--- a/upstart-jobs/httpd.nix
+++ b/upstart-jobs/httpd.nix
@@ -48,6 +48,7 @@ let
 
           notificationSender = getCfgSvn "notificationSender";
           autoVersioning = getCfgSvn "autoVersioning";
+          userCreationDomain = getCfgSvn "userCreationDomain";
 
           inherit pkgs;
         })