diff --git a/CHANGELOG.md b/CHANGELOG.md
index 326e0cb98dd..90d09090ed1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -41,6 +41,7 @@
 - Fix so vCard output does not contain non-standard/redundant TYPE=OTHER and TYPE=INTERNET (#8838)
 - Fix QR code images for contacts with non-ASCII characters (#9001)
 - Fix PHP8 warnings when using list_flags and list_cols properties by plugins (#8998)
+- Fix bug where subfolders could loose subscription on parent folder rename (#8892)
 
 ## Release 1.6.1
 
diff --git a/program/actions/settings/folder_edit.php b/program/actions/settings/folder_edit.php
index 2caebc36118..134ccc02e21 100644
--- a/program/actions/settings/folder_edit.php
+++ b/program/actions/settings/folder_edit.php
@@ -84,7 +84,7 @@ public static function folder_form($attrib)
         if (strlen($path)) {
             $path_id = $path;
             $path    = $storage->mod_folder($path . $delimiter);
-            if ($path[strlen($path)-1] == $delimiter) {
+            if (($path[strlen($path)-1] ?? '') == $delimiter) {
                 $path = substr($path, 0, -1);
             }
         }
diff --git a/program/lib/Roundcube/rcube_imap.php b/program/lib/Roundcube/rcube_imap.php
index aa4282a0422..addc2577bc3 100644
--- a/program/lib/Roundcube/rcube_imap.php
+++ b/program/lib/Roundcube/rcube_imap.php
@@ -3374,7 +3374,7 @@ public function rename_folder($folder, $new_name)
 
         // get list of subscribed folders
         if ((strpos($folder, '%') === false) && (strpos($folder, '*') === false)) {
-            $a_subscribed = $this->list_folders_subscribed('', $folder . $delm . '*');
+            $a_subscribed = $this->list_folders_subscribed($folder . $delm, '*');
             $subscribed   = $this->folder_exists($folder, true);
         }
         else {
@@ -3429,7 +3429,7 @@ public function delete_folder($folder)
         // get list of sub-folders or all folders
         // if folder name contains special characters
         $path       = strpos($folder, '*') === false && strpos($folder, '%') === false ? ($folder . $delm) : '';
-        $sub_mboxes = $this->list_folders('', $path . '*');
+        $sub_mboxes = $this->list_folders($path, '*');
 
         // According to RFC3501 deleting a \Noselect folder
         // with subfolders may fail. To workaround this we delete