diff --git a/src/lib/langPack.ts b/src/lib/langPack.ts
index 7413b796..6dc55ab7 100644
--- a/src/lib/langPack.ts
+++ b/src/lib/langPack.ts
@@ -114,6 +114,7 @@ namespace I18n {
     timeFormat = format;
 
     if(haveToUpdate) {
+      cachedDateTimeFormats.clear();
       const elements = Array.from(document.querySelectorAll(`.i18n`)) as HTMLElement[];
       elements.forEach(element => {
         const instance = weakMap.get(element);