diff --git a/src/api/viewService.ts b/src/api/viewService.ts
index 76d4990..8a5e013 100644
--- a/src/api/viewService.ts
+++ b/src/api/viewService.ts
@@ -256,8 +256,8 @@ export function getFormScreen(
 ): Promise<FormScreenResponse> {
   return request("POST", `/app/${APP_ID}/view/form-screens`, {
     activity_id: activityId,
-    instance_id: instanceId || "",
     device_type: deviceType,
+    ...(instanceId ? { instance_id: instanceId } : {}),
   });
 }