diff --git a/includes/log-handlers/class-wc-log-handler-file.php b/includes/log-handlers/class-wc-log-handler-file.php
index 7b915543902..3b4148cc623 100644
--- a/includes/log-handlers/class-wc-log-handler-file.php
+++ b/includes/log-handlers/class-wc-log-handler-file.php
@@ -65,6 +65,8 @@ class WC_Log_Handler_File extends WC_Log_Handler {
 	 *     Additional information for log handlers.
 	 *
 	 *     @type string $tag Optional. Determines log file to write to. Default 'log'.
+	 *     @type bool $_legacy Optional. Default false. True to use outdated log format
+	 *         orignally used in deprecated WC_Logger::add calls.
 	 * }
 	 *
 	 * @return bool False if value was not handled and true if value was handled.