diff --git a/app/mission-tab/[missionId]/page.tsx b/app/mission-tab/[missionId]/page.tsx
index 1c6e470..c541162 100644
--- a/app/mission-tab/[missionId]/page.tsx
+++ b/app/mission-tab/[missionId]/page.tsx
@@ -469,7 +469,7 @@ export default function MissionTabDetailPage() {
                     return true;
                   };
                   return isValid(mission.outlineCollectionId);
-                })() && (() => {
+                })() && mission.outlineCollectionId && (() => {
                   // Build Outline URL: chapitre.slm-lab.net/collection/[collectionId]
                   // If it's already a full URL, use it; otherwise build from ID
                   const outlineUrl = mission.outlineCollectionId.startsWith('http')