diff --git a/main/inc/ajax/forum.ajax.php b/main/inc/ajax/forum.ajax.php
index b8b679cadd..02211887b2 100644
--- a/main/inc/ajax/forum.ajax.php
+++ b/main/inc/ajax/forum.ajax.php
@@ -110,13 +110,18 @@ if (!empty($action)) {
                 // The only exception is the course manager
                 // They are several pieces for clarity.
                 if (!api_is_allowed_to_edit(null, true) AND
-                    (($current_forum_category && $current_forum_category['visibility'] == 0) OR $current_forum['visibility'] == 0)
+                    (
+                        ($current_forum_category && $current_forum_category['visibility'] == 0) OR
+                        $current_forum['visibility'] == 0)
                 ) {
                     $json['errorMessage'] = '1. the forum category, forum or thread is invisible (visibility==0)';
                     break;
                 }
                 if (!api_is_allowed_to_edit(null, true) AND
-                    (($current_forum_category && $current_forum_category['locked'] <> 0) OR $current_forum['locked'] <> 0 OR $current_thread['locked'] <> 0)
+                    (
+                        ($current_forum_category && $current_forum_category['locked'] <> 0) OR
+                        $current_forum['locked'] <> 0 OR $current_thread['locked'] <> 0
+                    )
                 ) {
                     $json['errorMessage'] = '2. the forum category, forum or thread is locked (locked <>0)';
                     break;
@@ -128,7 +133,7 @@ if (!empty($action)) {
                 $group_id = api_get_group_id();
                 if (!api_is_allowed_to_edit(null, true) AND
                     $current_forum['allow_edit'] == 0 &&
-                    !GroupManager::is_tutor_of_group(api_get_user_id(), $group_id)
+                    ($group_id && !GroupManager::is_tutor_of_group(api_get_user_id(), $group_id))
                 ) {
                     $json['errorMessage'] = '4. if editing of replies is not allowed';
                     break;