diff --git a/booking.variety_admin.inc b/booking.variety_admin.inc
index 52ffc5a..2baf8b9 100644
--- a/booking.variety_admin.inc
+++ b/booking.variety_admin.inc
@@ -772,7 +772,7 @@ function booking_variety_regn_edit_form_submit($form, &$form_state) {
 
         // increase regn count for new session
         db_update('booking_variety_sessions')
-          ->expression('booking_variety_regncount', 'booking_variety_regncount - :count', array(':count' => 1))
+          ->expression('booking_variety_regncount', 'booking_variety_regncount + :count', array(':count' => 1))
           ->condition('vid', $booking_variety_ids[$previous_tid])
           ->execute();