diff --git a/src/services/questService.ts b/src/services/questService.ts
index 9a21f991..cc9449fd 100644
--- a/src/services/questService.ts
+++ b/src/services/questService.ts
@@ -83,10 +83,16 @@ export const updateQuestStage = (
             `Quest stage index mismatch: stage is ${ChainStage} but array size is ${quest.Progress.length}`
         );
     }
-    const questStage = quest.Progress[ChainStage]; // guaranteed in-bounds now
+    // Note that the client may use index 0 as well, e.g. for rising tide's initial inbox message. 'm' is not tracked for it.
+    if (ChainStage >= 0) {
+        const questStage = quest.Progress[ChainStage]; // guaranteed in-bounds now
 
-    for (const [key, value] of Object.entries(questStageUpdate) as [keyof IQuestStage, number | boolean | any[]][]) {
-        (questStage[key] as any) = value;
+        for (const [key, value] of Object.entries(questStageUpdate) as [
+            keyof IQuestStage,
+            number | boolean | any[]
+        ][]) {
+            (questStage[key] as any) = value;
+        }
     }
 };