diff --git a/src/models/inventoryModels/inventoryModel.ts b/src/models/inventoryModels/inventoryModel.ts
index 775ac280..76ef9edf 100644
--- a/src/models/inventoryModels/inventoryModel.ts
+++ b/src/models/inventoryModels/inventoryModel.ts
@@ -888,7 +888,7 @@ const inventorySchema = new Schema<IInventoryDatabase, InventoryDocumentProps>(
         ChallengesFixVersion: Number,
         PlayedParkourTutorial: Boolean,
         SubscribedToEmailsPersonalized: Number,
-        LastInventorySync: Schema.Types.ObjectId,
+        LastInventorySync: Schema.Types.Mixed, // this should be Schema.Types.ObjectId, but older inventories may break with that.
         ActiveLandscapeTraps: [Schema.Types.Mixed],
         RepVotes: [Schema.Types.Mixed],
         LeagueTickets: [Schema.Types.Mixed],