diff --git a/src/MoonOptions.ts b/src/MoonOptions.ts
index 83af828..c85b4e1 100644
--- a/src/MoonOptions.ts
+++ b/src/MoonOptions.ts
@@ -1,5 +1,5 @@
 import { Hemisphere } from "./constants/Hemisphere";
 
 export type MoonOptions = {
-  hemisphere?: Hemisphere | undefined;
+  hemisphere?: Hemisphere;
 };