diff --git a/src/core_plugins/kibana/ui_setting_defaults.js b/src/core_plugins/kibana/ui_setting_defaults.js
index 3b43d99550313b..76b916656e5545 100644
--- a/src/core_plugins/kibana/ui_setting_defaults.js
+++ b/src/core_plugins/kibana/ui_setting_defaults.js
@@ -24,9 +24,11 @@ import { IS_KIBANA_RELEASE } from '../../utils';
 export function getUiSettingDefaults() {
   const weekdays = moment.weekdays().slice();
   const [defaultWeekday] = weekdays;
-  const numeralLanguageIds = numeralLanguages.map(function (numeralLanguage) {
+  // We add the `en` key manually here, since that's not a real numeral locale, but the
+  // default fallback in case the locale is not found.
+  const numeralLanguageIds = ['en', ...numeralLanguages.map(function (numeralLanguage) {
     return numeralLanguage.id;
-  });
+  })];
 
   // wrapped in provider so that a new instance is given to each app/test
   return {