diff --git a/modules/user/user.module b/modules/user/user.module
index 8917192..7d89d40 100644
--- a/modules/user/user.module
+++ b/modules/user/user.module
@@ -233,7 +233,8 @@ function user_save($account, $array = array(), $category = 'account') {
         }
         else if ($key != 'roles') {
           // Roles is a special case: it used below.
-          if ($value === NULL) {
+          if ($value === NULL || $key == 'form_build_id') {
+            // Remove the form_build_id that was set by previous Drupal versions - bug #219105
             unset($data[$key]);
           }
           elseif (!empty($key)) {