diff --git a/src/govuk/i18n.mjs b/src/govuk/i18n.mjs
index 40050c1faa..e398907fde 100644
--- a/src/govuk/i18n.mjs
+++ b/src/govuk/i18n.mjs
@@ -211,7 +211,7 @@ I18n.prototype.selectPluralFormUsingFallbackRules = function (count) {
  * regardless of region. There are exceptions, however, (e.g. Portuguese) so
  * this searches by both the full and shortened locale codes, just to be sure.
  *
- * @returns {PluralRuleName | undefined} The name of the pluralisation rule to use (a key for one
+ * @returns {string | undefined} The name of the pluralisation rule to use (a key for one
  *   of the functions in this.pluralRules)
  */
 I18n.prototype.getPluralRulesForLocale = function () {
@@ -262,7 +262,7 @@ I18n.prototype.getPluralRulesForLocale = function () {
  * Spanish: European Portuguese (pt-PT), Italian (it), Spanish (es)
  * Welsh: Welsh (cy)
  *
- * @type {Object<PluralRuleName, string[]>}
+ * @type {Object<string, string[]>}
  */
 I18n.pluralRulesMap = {
   arabic: ['ar'],
@@ -350,12 +350,6 @@ I18n.pluralRules = {
   /* eslint-enable jsdoc/require-jsdoc */
 }
 
-/**
- * Supported languages for plural rules
- *
- * @typedef {'arabic' | 'chinese' | 'french' | 'german' | 'irish' | 'russian' | 'scottish' | 'spanish' | 'welsh'} PluralRuleName
- */
-
 /**
  * Plural rule category mnemonic tags
  *