diff --git a/src/settings/handlers/RoomDeviceSettingsHandler.js b/src/settings/handlers/RoomDeviceSettingsHandler.ts
similarity index 66%
rename from src/settings/handlers/RoomDeviceSettingsHandler.js
rename to src/settings/handlers/RoomDeviceSettingsHandler.ts
index cd1f9e9265..2fcd58c27c 100644
--- a/src/settings/handlers/RoomDeviceSettingsHandler.js
+++ b/src/settings/handlers/RoomDeviceSettingsHandler.ts
@@ -1,6 +1,6 @@
 /*
 Copyright 2017 Travis Ralston
-Copyright 2019 New Vector Ltd.
+Copyright 2019, 2020 The Matrix.org Foundation C.I.C.
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
@@ -16,71 +16,70 @@ limitations under the License.
 */
 
 import SettingsHandler from "./SettingsHandler";
-import {SettingLevel} from "../SettingLevel";
+import { SettingLevel } from "../SettingLevel";
+import { WatchManager } from "../WatchManager";
 
 /**
  * Gets and sets settings at the "room-device" level for the current device in a particular
  * room.
  */
 export default class RoomDeviceSettingsHandler extends SettingsHandler {
-    constructor(watchManager) {
+    constructor(private watchers: WatchManager) {
         super();
-
-        this._watchers = watchManager;
     }
 
-    getValue(settingName, roomId) {
+    public getValue(settingName: string, roomId: string): any {
         // Special case blacklist setting to use legacy values
         if (settingName === "blacklistUnverifiedDevices") {
-            const value = this._read("mx_local_settings");
+            const value = this.read("mx_local_settings");
             if (value && value['blacklistUnverifiedDevicesPerRoom']) {
                 return value['blacklistUnverifiedDevicesPerRoom'][roomId];
             }
         }
 
-        const value = this._read(this._getKey(settingName, roomId));
+        const value = this.read(this.getKey(settingName, roomId));
         if (value) return value.value;
         return null;
     }
 
-    setValue(settingName, roomId, newValue) {
+    public setValue(settingName: string, roomId: string, newValue: any): Promise<void> {
         // Special case blacklist setting for legacy structure
         if (settingName === "blacklistUnverifiedDevices") {
-            let value = this._read("mx_local_settings");
+            let value = this.read("mx_local_settings");
             if (!value) value = {};
             if (!value["blacklistUnverifiedDevicesPerRoom"]) value["blacklistUnverifiedDevicesPerRoom"] = {};
             value["blacklistUnverifiedDevicesPerRoom"][roomId] = newValue;
             localStorage.setItem("mx_local_settings", JSON.stringify(value));
-            this._watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
+            this.watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
             return Promise.resolve();
         }
 
         if (newValue === null) {
-            localStorage.removeItem(this._getKey(settingName, roomId));
+            localStorage.removeItem(this.getKey(settingName, roomId));
         } else {
             newValue = JSON.stringify({value: newValue});
-            localStorage.setItem(this._getKey(settingName, roomId), newValue);
+            localStorage.setItem(this.getKey(settingName, roomId), newValue);
         }
 
-        this._watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
+        this.watchers.notifyUpdate(settingName, roomId, SettingLevel.ROOM_DEVICE, newValue);
         return Promise.resolve();
     }
 
-    canSetValue(settingName, roomId) {
+    public canSetValue(settingName: string, roomId: string): boolean {
         return true; // It's their device, so they should be able to
     }
 
-    isSupported() {
+    public isSupported(): boolean {
         return localStorage !== undefined && localStorage !== null;
     }
 
-    _read(key) {
+    private read(key: string): any {
         const rawValue = localStorage.getItem(key);
         if (!rawValue) return null;
         return JSON.parse(rawValue);
     }
 
-    _getKey(settingName, roomId) {
+    private getKey(settingName: string, roomId: string): string {
         return "mx_setting_" + settingName + "_" + roomId;
     }
 }
diff --git a/src/settings/handlers/SettingsHandler.ts b/src/settings/handlers/SettingsHandler.ts
index 53adb9aca6..4b1c3459da 100644
--- a/src/settings/handlers/SettingsHandler.ts
+++ b/src/settings/handlers/SettingsHandler.ts
@@ -44,7 +44,7 @@ export default abstract class SettingsHandler {
      * @param {*} newValue The new value for the setting, may be null.
      * @returns {Promise} Resolves when the setting has been saved.
      */
-    public setValue(settingName: string, roomId: string, newValue): Promise<void> {
+    public setValue(settingName: string, roomId: string, newValue: any): Promise<void> {
         console.error("Invalid operation: setValue was not overridden");
         return Promise.reject(new Error("Invalid operation: setValue was not overridden"));
     }