diff --git a/packages/design-studio/test/manual.test.ts b/packages/design-studio/test/manual.test.ts
index fd8cabc2..dabe2fec 100644
--- a/packages/design-studio/test/manual.test.ts
+++ b/packages/design-studio/test/manual.test.ts
@@ -95,7 +95,7 @@ test("manual form saves one atomic revision and rejects locked changes without c
   try {
     (globalThis as any).document = win.document;
     (globalThis as any).HTMLInputElement = win.HTMLInputElement;
-    (globalThis as any).Option = win.Option;
+    (globalThis as any).Option = (win as any).Option;
     win.document.body.innerHTML =
       manualHtml + '<select id="preview-mode"><option value="light">light</option></select>';
     const session = new StudioSession(CORE_DESIGN_SYSTEMS.soft);