diff --git a/frontend/src/lib/daily-starlanguage.ts b/frontend/src/lib/daily-starlanguage.ts
index 466b8d32..6e48f64d 100644
--- a/frontend/src/lib/daily-starlanguage.ts
+++ b/frontend/src/lib/daily-starlanguage.ts
@@ -291,7 +291,7 @@ function moonHouse(evidence: DailyStarlanguageEvidence): number | null {
 export function composeDailyStarlanguageCard(evidence: DailyStarlanguageEvidence): DailyStarlanguageCard {
   const house = moonHouse(evidence);
   const theme = house ? HOUSE_THEMES[house] : undefined;
-  const mahadasha = planetZh(evidence.vimshottari?.mahadasha);
+  const mahadasha = planetZh(evidence.vimshottari?.mahadasha ?? null);
   const triggers = evidence.transit?.totalTriggers ?? 0;
   const trend = theme && mahadasha
     ? `今天${theme.theme}的节奏更明显，${mahadasha}大运里适合先把一件小事做完。`