diff --git a/db_structure.php b/db_structure.php
index 07218a5cf..b66eb8e93 100644
--- a/db_structure.php
+++ b/db_structure.php
@@ -29,7 +29,7 @@ if (empty($is_info)) {
         // db_structure.php -> libraries/mult_submits.inc.php -> sql.php
         // -> db_structure.php and if we got an error on the multi submit,
         // we must display it here and not call again mult_submits.inc.php
-        if (!$error) {
+        if (! isset($error) || FALSE === $error) {
             require './libraries/mult_submits.inc.php';
         }
         if (empty($message)) {