diff --git a/src/controllers/api/inventoryController.ts b/src/controllers/api/inventoryController.ts
index 59c3415e..6d2db473 100644
--- a/src/controllers/api/inventoryController.ts
+++ b/src/controllers/api/inventoryController.ts
@@ -29,6 +29,7 @@ import { version_compare } from "@/src/services/worldStateService";
 import { getPersonalRooms } from "@/src/services/personalRoomsService";
 import { IPersonalRoomsClient } from "@/src/types/personalRoomsTypes";
 import { Ship } from "@/src/models/shipModel";
+import { toLegacyOid } from "@/src/helpers/inventoryHelpers";
 
 export const inventoryController: RequestHandler = async (request, response) => {
     const account = await getAccountForRequest(request);
@@ -306,19 +307,29 @@ export const getInventoryResponse = async (
     // Set 2FA enabled so trading post can be used
     inventoryResponse.HWIDProtectEnabled = true;
 
-    // Fix nemesis for older versions
-    if (
-        inventoryResponse.Nemesis &&
-        buildLabel &&
-        !isNemesisCompatibleWithVersion(inventoryResponse.Nemesis, buildLabel)
-    ) {
-        inventoryResponse.Nemesis = undefined;
-    }
+    if (buildLabel) {
+        // Fix nemesis for older versions
+        if (inventoryResponse.Nemesis && !isNemesisCompatibleWithVersion(inventoryResponse.Nemesis, buildLabel)) {
+            inventoryResponse.Nemesis = undefined;
+        }
 
-    if (buildLabel && version_compare(buildLabel, "2018.02.22.14.34") < 0) {
-        const personalRoomsDb = await getPersonalRooms(inventory.accountOwnerId.toString());
-        const personalRooms = personalRoomsDb.toJSON<IPersonalRoomsClient>();
-        inventoryResponse.Ship = personalRooms.Ship;
+        if (version_compare(buildLabel, "2018.02.22.14.34") < 0) {
+            const personalRoomsDb = await getPersonalRooms(inventory.accountOwnerId.toString());
+            const personalRooms = personalRoomsDb.toJSON<IPersonalRoomsClient>();
+            inventoryResponse.Ship = personalRooms.Ship;
+
+            if (version_compare(buildLabel, "2017.03.06.15.49") < 0) {
+                // U19.4 and below use $id instead of $oid
+                for (const category of equipmentKeys) {
+                    for (const item of inventoryResponse[category]) {
+                        toLegacyOid(item.ItemId);
+                    }
+                }
+                for (const upgrade of inventoryResponse.Upgrades) {
+                    toLegacyOid(upgrade.ItemId);
+                }
+            }
+        }
     }
 
     return inventoryResponse;
diff --git a/src/helpers/inventoryHelpers.ts b/src/helpers/inventoryHelpers.ts
index 5efc801d..0e64c818 100644
--- a/src/helpers/inventoryHelpers.ts
+++ b/src/helpers/inventoryHelpers.ts
@@ -1,4 +1,4 @@
-import { IMongoDate, IOid } from "@/src/types/commonTypes";
+import { IMongoDate, IOid, IOidWithLegacySupport } from "@/src/types/commonTypes";
 import { Types } from "mongoose";
 import { TRarity } from "warframe-public-export-plus";
 
@@ -6,6 +6,17 @@ export const toOid = (objectId: Types.ObjectId): IOid => {
     return { $oid: objectId.toString() } satisfies IOid;
 };
 
+export const toLegacyOid = (oid: IOidWithLegacySupport): void => {
+    if (!("$id" in oid)) {
+        oid.$id = oid.$oid;
+        delete oid.$oid;
+    }
+};
+
+export const fromOid = (oid: IOidWithLegacySupport): string => {
+    return (oid.$oid ?? oid.$id)!;
+};
+
 export const toMongoDate = (date: Date): IMongoDate => {
     return { $date: { $numberLong: date.getTime().toString() } };
 };
diff --git a/src/services/inventoryService.ts b/src/services/inventoryService.ts
index 6a30df38..4111209c 100644
--- a/src/services/inventoryService.ts
+++ b/src/services/inventoryService.ts
@@ -70,6 +70,7 @@ import { createShip } from "./shipService";
 import {
     catbrowDetails,
     fromMongoDate,
+    fromOid,
     kubrowDetails,
     kubrowFurPatternsWeights,
     kubrowWeights,
@@ -1491,9 +1492,9 @@ export const applyClientEquipmentUpdates = (
     const category = inventory[categoryName];
 
     gearArray.forEach(({ ItemId, XP, InfestationDate }) => {
-        const item = category.id(ItemId.$oid);
+        const item = category.id(fromOid(ItemId));
         if (!item) {
-            throw new Error(`No item with id ${ItemId.$oid} in ${categoryName}`);
+            throw new Error(`No item with id ${fromOid(ItemId)} in ${categoryName}`);
         }
 
         if (XP) {
diff --git a/src/services/missionInventoryUpdateService.ts b/src/services/missionInventoryUpdateService.ts
index decc74ba..a585dceb 100644
--- a/src/services/missionInventoryUpdateService.ts
+++ b/src/services/missionInventoryUpdateService.ts
@@ -62,6 +62,7 @@ import { getLiteSortie, getSortie, idToBountyCycle, idToDay, idToWeek, pushClass
 import { config } from "./configService";
 import libraryDailyTasks from "@/static/fixed_responses/libraryDailyTasks.json";
 import { ISyndicateMissionInfo } from "../types/worldStateTypes";
+import { fromOid } from "../helpers/inventoryHelpers";
 
 const getRotations = (rewardInfo: IRewardInfo, tierOverride?: number): number[] => {
     // For Spy missions, e.g. 3 vaults cracked = A, B, C
@@ -399,7 +400,7 @@ export const addMissionInventoryUpdates = async (
                 break;
             case "Upgrades":
                 value.forEach(clientUpgrade => {
-                    const upgrade = inventory.Upgrades.id(clientUpgrade.ItemId.$oid)!;
+                    const upgrade = inventory.Upgrades.id(fromOid(clientUpgrade.ItemId))!;
                     upgrade.UpgradeFingerprint = clientUpgrade.UpgradeFingerprint; // primitive way to copy over the riven challenge progress
                 });
                 break;
diff --git a/src/types/commonTypes.ts b/src/types/commonTypes.ts
index 5ac1cac3..a9335fff 100644
--- a/src/types/commonTypes.ts
+++ b/src/types/commonTypes.ts
@@ -4,6 +4,11 @@ export interface IOid {
     $oid: string;
 }
 
+export interface IOidWithLegacySupport {
+    $oid?: string;
+    $id?: string;
+}
+
 export interface IMongoDate {
     $date: {
         $numberLong: string;
diff --git a/src/types/inventoryTypes/commonInventoryTypes.ts b/src/types/inventoryTypes/commonInventoryTypes.ts
index 37168a7d..8cc0d56f 100644
--- a/src/types/inventoryTypes/commonInventoryTypes.ts
+++ b/src/types/inventoryTypes/commonInventoryTypes.ts
@@ -1,4 +1,4 @@
-import { IMongoDate, IOid } from "@/src/types/commonTypes";
+import { IMongoDate, IOid, IOidWithLegacySupport } from "@/src/types/commonTypes";
 import { Types } from "mongoose";
 import {
     ICrewShipCustomization,
@@ -92,7 +92,7 @@ export interface IEquipmentClient
         IEquipmentDatabase,
         "_id" | "InfestationDate" | "Expiry" | "UpgradesExpiry" | "UmbraDate" | "CrewMembers" | "Details"
     > {
-    ItemId: IOid;
+    ItemId: IOidWithLegacySupport;
     InfestationDate?: IMongoDate;
     Expiry?: IMongoDate;
     UpgradesExpiry?: IMongoDate;