diff --git a/app/Models/Transformer/Driver/FluxBB/FluxBB.php b/app/Models/Transformer/Driver/FluxBB/FluxBB.php
index da91dca..da445a2 100644
--- a/app/Models/Transformer/Driver/FluxBB/FluxBB.php
+++ b/app/Models/Transformer/Driver/FluxBB/FluxBB.php
@@ -45,7 +45,7 @@ class FluxBB extends AbstractDriver
     /**
      * @var string
      */
-    protected $min = '1.5.8';
+    protected $min = '1.5.7';
 
     /**
      * @var string
@@ -192,7 +192,7 @@ public function groupsGet(int &$id): ?array
             'g_mod_rename_users'     => (int) $vars['g_mod_rename_users'],
             'g_mod_change_passwords' => (int) $vars['g_mod_change_passwords'],
             'g_mod_ban_users'        => (int) $vars['g_mod_ban_users'],
-            'g_mod_promote_users'    => (int) $vars['g_mod_promote_users'],
+            'g_mod_promote_users'    => (int) ($vars['g_mod_promote_users'] ?? 0),
             'g_read_board'           => (int) $vars['g_read_board'],
             'g_view_users'           => (int) $vars['g_view_users'],
             'g_post_replies'         => (int) $vars['g_post_replies'],
diff --git a/app/Models/Transformer/Driver/FluxBB_by_Visman/FluxBB_by_Visman.php b/app/Models/Transformer/Driver/FluxBB_by_Visman/FluxBB_by_Visman.php
index 522fea8..3bede94 100644
--- a/app/Models/Transformer/Driver/FluxBB_by_Visman/FluxBB_by_Visman.php
+++ b/app/Models/Transformer/Driver/FluxBB_by_Visman/FluxBB_by_Visman.php
@@ -201,7 +201,7 @@ public function groupsGet(int &$id): ?array
             'g_mod_rename_users'     => (int) $vars['g_mod_rename_users'],
             'g_mod_change_passwords' => (int) $vars['g_mod_change_passwords'],
             'g_mod_ban_users'        => (int) $vars['g_mod_ban_users'],
-            'g_mod_promote_users'    => (int) $vars['g_mod_promote_users'],
+            'g_mod_promote_users'    => (int) ($vars['g_mod_promote_users'] ?? 0),
             'g_read_board'           => (int) $vars['g_read_board'],
             'g_view_users'           => (int) $vars['g_view_users'],
             'g_post_replies'         => (int) $vars['g_post_replies'],
diff --git a/readme.md b/readme.md
index 5c2c70d..bc9d9bc 100644
--- a/readme.md
+++ b/readme.md
@@ -9,7 +9,7 @@ Transformer is a script to convert/merge another forum's database to/with ForkBB
 Supports (convert/merge):
 1. ForkBB rev.42 - rev.48
 2. FluxBB_by_Visman rev.78 - rev.83
-3. FluxBB 1.5.8 - 1.5.11
+3. FluxBB 1.5.7 - 1.5.11
 
 ## Requirements