diff --git a/phpBB/includes/acp/acp_storage.php b/phpBB/includes/acp/acp_storage.php
index 74cb64e76c..9998188a18 100644
--- a/phpBB/includes/acp/acp_storage.php
+++ b/phpBB/includes/acp/acp_storage.php
@@ -79,8 +79,8 @@ class acp_storage
 
 	public function overview($id, $mode)
 	{
-		$form_name = 'acp_storage';
-		add_form_key($form_name);
+		$form_key = 'acp_storage';
+		add_form_key($form_key);
 
 		// Template from adm/style
 		$this->tpl_name = 'acp_storage';
@@ -93,6 +93,11 @@ class acp_storage
 			$modified_storages = [];
 			$messages = [];
 
+			if (!check_form_key($form_key))
+			{
+				$messages[] = $this->lang->lang('FORM_INVALID');
+			}
+
 			foreach ($this->storage_collection as $storage)
 			{
 				$storage_name = $storage->get_name();