diff --git a/webapp/controller/UserController.class.php b/webapp/controller/UserController.class.php
index 847651c9..0ea79894 100644
--- a/webapp/controller/UserController.class.php
+++ b/webapp/controller/UserController.class.php
@@ -503,8 +503,8 @@ class UserController extends BaseAuthedController {
         $errCod = 0;
         $errMsg = '';
         foreach ($validFields as $key => $field) {
-            $reqVal = getReqVal($key, '');
-            if (!empty($reqVal)) {
+            $reqVal = getReqVal($key, null);
+            if (!is_null($reqVal)) {
                 if (isset($field['valid_func'])) {
                     if (!$field['valid_func']($reqVal, $errCod, $errMsg)) {
                         $this->_rspErr($errCod, $errMsg);