diff --git a/src/services/missionInventoryUpdateService.ts b/src/services/missionInventoryUpdateService.ts
index f452c6a5..d6457f96 100644
--- a/src/services/missionInventoryUpdateService.ts
+++ b/src/services/missionInventoryUpdateService.ts
@@ -364,7 +364,7 @@ export const addMissionInventoryUpdates = async (
             }
             case "DeathMarks": {
                 for (const deathMark of value) {
-                    if (!inventory.DeathMarks.find(x => x == deathMark)) {
+                    if (inventory.DeathMarks.indexOf(deathMark) == -1) {
                         // It's a new death mark; we have to say the line.
                         await createMessage(inventory.accountOwnerId, [
                             {