diff --git a/src/common/I18n.js b/src/common/I18n.js
index 7876ed2..bd5f29f 100644
--- a/src/common/I18n.js
+++ b/src/common/I18n.js
@@ -8,7 +8,7 @@ class I18n {
    * Constructor.
    *
    * @param {Object} options Options.
-   * @param {string} options.locale Locale.
+   * @param {string=} options.locale Locale.
    * @param {Object} options.translations Translations.
    */
   constructor({ locale, translations }) {