Index: includes/registration.forms.inc
===================================================================
--- includes/registration.forms.inc	(revision 4702)
+++ includes/registration.forms.inc	(working copy)
@@ -28,7 +28,8 @@ function registration_form($form, &$form
     $who_default = $registration->registrant_type($GLOBALS['user']);
   }
   elseif (count($who_options) == 1) {
-    $who_default = reset(array_keys($who_options));
+    $who_keys = array_keys($who_options);
+    $who_default = reset($who_keys);
   }
 
   // show a message if there's only one option as we're going to hide the form