diff --git a/types/plugin/timezone.d.ts b/types/plugin/timezone.d.ts
index dce3b8b06..015e45ba2 100644
--- a/types/plugin/timezone.d.ts
+++ b/types/plugin/timezone.d.ts
@@ -11,6 +11,7 @@ declare module 'dayjs' {
   interface DayjsTimezone {
     (date: ConfigType, timezone: string): Dayjs
     guess(): string
+    setDefault(timezone?: string): void
   }
 
   const tz: DayjsTimezone