diff --git a/src/client.ts b/src/client.ts
index 0c2a83f39..7cc9c601a 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -490,6 +490,7 @@ interface IKeyBackupPath {
 }
 
 interface IMediaConfig {
+    [key: string]: any; // extensible
     "m.upload.size"?: number;
 }
 
@@ -4374,14 +4375,12 @@ export class MatrixClient extends EventEmitter {
     // eslint-disable-next-line camelcase
     public setProfileInfo(info: "avatar_url", data: { avatar_url: string }, callback?: Callback): Promise<{}>;
     public setProfileInfo(info: "displayname", data: { displayname: string }, callback?: Callback): Promise<{}>;
-    public setProfileInfo(info: string, data: object, callback?: Callback): Promise<{}> {
+    public setProfileInfo(info: "avatar_url" | "displayname", data: object, callback?: Callback): Promise<{}> {
         const path = utils.encodeUri("/profile/$userId/$info", {
             $userId: this.credentials.userId,
             $info: info,
         });
-        return this.http.authedRequest(
-            callback, "PUT", path, undefined, data,
-        );
+        return this.http.authedRequest(callback, "PUT", path, undefined, data);
     }
 
     /**
diff --git a/src/crypto/EncryptionSetup.ts b/src/crypto/EncryptionSetup.ts
index 8b538afa2..faa4bd2e8 100644
--- a/src/crypto/EncryptionSetup.ts
+++ b/src/crypto/EncryptionSetup.ts
@@ -1,3 +1,19 @@
+/*
+Copyright 2021 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.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
 import { logger } from "../logger";
 import { MatrixEvent } from "../models/event";
 import { EventEmitter } from "events";
diff --git a/src/filter.ts b/src/filter.ts
index 618c727c3..8cbd2a67e 100644
--- a/src/filter.ts
+++ b/src/filter.ts
@@ -86,7 +86,7 @@ export class Filter {
      * @param {Object} jsonObj
      * @return {Filter}
      */
-    static fromJson(userId: string, filterId: string, jsonObj: IFilterDefinition): Filter {
+    public static fromJson(userId: string, filterId: string, jsonObj: IFilterDefinition): Filter {
         const filter = new Filter(userId, filterId);
         filter.setDefinition(jsonObj);
         return filter;
diff --git a/src/models/room.ts b/src/models/room.ts
index 716da1214..65abbd099 100644
--- a/src/models/room.ts
+++ b/src/models/room.ts
@@ -25,7 +25,7 @@ import { EventTimeline } from "./event-timeline";
 import { getHttpUriForMxc } from "../content-repo";
 import * as utils from "../utils";
 import { normalize } from "../utils";
-import { EventStatus, MatrixEvent } from "./event";
+import { EventStatus, IEvent, MatrixEvent } from "./event";
 import { RoomMember } from "./room-member";
 import { IRoomSummary, RoomSummary } from "./room-summary";
 import { logger } from '../logger';
@@ -35,6 +35,7 @@ import { IRoomVersionsCapability, MatrixClient, PendingEventOrdering, RoomVersio
 import { ResizeMethod } from "../@types/partials";
 import { Filter } from "../filter";
 import { RoomState } from "./room-state";
+import { IMinimalEvent } from "../sync-accumulator";
 
 // These constants are used as sane defaults when the homeserver doesn't support
 // the m.room_versions capability. In practice, KNOWN_SAFE_ROOM_VERSION should be
@@ -649,7 +650,7 @@ export class Room extends EventEmitter {
         }
     }
 
-    private async loadMembersFromServer(): Promise<object[]> {
+    private async loadMembersFromServer(): Promise<IEvent[]> {
         const lastSyncToken = this.client.store.getSyncToken();
         const queryString = utils.encodeParams({
             not_membership: "leave",
@@ -712,7 +713,7 @@ export class Room extends EventEmitter {
             if (fromServer) {
                 const oobMembers = this.currentState.getMembers()
                     .filter((m) => m.isOutOfBand())
-                    .map((m) => m.events.member.event);
+                    .map((m) => m.events.member.event as IEvent);
                 logger.log(`LL: telling store to write ${oobMembers.length}`
                     + ` members for room ${this.roomId}`);
                 const store = this.client.store;
diff --git a/src/store/index.ts b/src/store/index.ts
index e835d3791..01650f86a 100644
--- a/src/store/index.ts
+++ b/src/store/index.ts
@@ -18,7 +18,7 @@ import { EventType } from "../@types/event";
 import { Group } from "../models/group";
 import { Room } from "../models/room";
 import { User } from "../models/user";
-import { MatrixEvent } from "../models/event";
+import { IEvent, MatrixEvent } from "../models/event";
 import { Filter } from "../filter";
 import { RoomSummary } from "../models/room-summary";
 import { IMinimalEvent, IGroups, IRooms } from "../sync-accumulator";
@@ -225,9 +225,9 @@ export interface IStore {
      */
     deleteAllData(): Promise<void>;
 
-    getOutOfBandMembers(roomId: string): Promise<object[] | null>;
+    getOutOfBandMembers(roomId: string): Promise<IEvent[] | null>;
 
-    setOutOfBandMembers(roomId: string, membershipEvents: object[]): Promise<void>;
+    setOutOfBandMembers(roomId: string, membershipEvents: IEvent[]): Promise<void>;
 
     clearOutOfBandMembers(roomId: string): Promise<void>;
 
diff --git a/src/store/indexeddb.ts b/src/store/indexeddb.ts
index f7f9fb8b9..aed61dae2 100644
--- a/src/store/indexeddb.ts
+++ b/src/store/indexeddb.ts
@@ -22,7 +22,7 @@ import { MemoryStore, IOpts as IBaseOpts } from "./memory";
 import { LocalIndexedDBStoreBackend } from "./indexeddb-local-backend.js";
 import { RemoteIndexedDBStoreBackend } from "./indexeddb-remote-backend.js";
 import { User } from "../models/user";
-import { MatrixEvent } from "../models/event";
+import { IEvent, MatrixEvent } from "../models/event";
 import { logger } from '../logger';
 import { ISavedSync } from "./index";
 
@@ -247,7 +247,7 @@ export class IndexedDBStore extends MemoryStore {
      * @returns {event[]} the events, potentially an empty array if OOB loading didn't yield any new members
      * @returns {null} in case the members for this room haven't been stored yet
      */
-    public getOutOfBandMembers = this.degradable((roomId: string): Promise<MatrixEvent[]> => {
+    public getOutOfBandMembers = this.degradable((roomId: string): Promise<IEvent[]> => {
         return this.backend.getOutOfBandMembers(roomId);
     }, "getOutOfBandMembers");
 
@@ -259,7 +259,7 @@ export class IndexedDBStore extends MemoryStore {
      * @param {event[]} membershipEvents the membership events to store
      * @returns {Promise} when all members have been stored
      */
-    public setOutOfBandMembers = this.degradable((roomId: string, membershipEvents: MatrixEvent[]): Promise<void> => {
+    public setOutOfBandMembers = this.degradable((roomId: string, membershipEvents: IEvent[]): Promise<void> => {
         super.setOutOfBandMembers(roomId, membershipEvents);
         return this.backend.setOutOfBandMembers(roomId, membershipEvents);
     }, "setOutOfBandMembers");
diff --git a/src/store/memory.ts b/src/store/memory.ts
index 94090f9c5..00dceb711 100644
--- a/src/store/memory.ts
+++ b/src/store/memory.ts
@@ -23,12 +23,13 @@ import { EventType } from "../@types/event";
 import { Group } from "../models/group";
 import { Room } from "../models/room";
 import { User } from "../models/user";
-import { MatrixEvent } from "../models/event";
+import { IEvent, MatrixEvent } from "../models/event";
 import { RoomState } from "../models/room-state";
 import { RoomMember } from "../models/room-member";
 import { Filter } from "../filter";
 import { ISavedSync, IStore } from "./index";
 import { RoomSummary } from "../models/room-summary";
+import { IMinimalEvent } from "../sync-accumulator";
 
 function isValidFilterId(filterId: string): boolean {
     const isValidStr = typeof filterId === "string" &&
@@ -61,7 +62,7 @@ export class MemoryStore implements IStore {
     private filters: Record<string, Record<string, Filter>> = {};
     public accountData: Record<string, MatrixEvent> = {}; // type : content
     private readonly localStorage: Storage;
-    private oobMembers: Record<string, MatrixEvent[]> = {}; // roomId: [member events]
+    private oobMembers: Record<string, IEvent[]> = {}; // roomId: [member events]
     private clientOptions = {};
 
     constructor(opts: IOpts = {}) {
@@ -415,7 +416,7 @@ export class MemoryStore implements IStore {
      * @returns {event[]} the events, potentially an empty array if OOB loading didn't yield any new members
      * @returns {null} in case the members for this room haven't been stored yet
      */
-    public getOutOfBandMembers(roomId: string): Promise<MatrixEvent[] | null> {
+    public getOutOfBandMembers(roomId: string): Promise<IEvent[] | null> {
         return Promise.resolve(this.oobMembers[roomId] || null);
     }
 
@@ -427,7 +428,7 @@ export class MemoryStore implements IStore {
      * @param {event[]} membershipEvents the membership events to store
      * @returns {Promise} when all members have been stored
      */
-    public setOutOfBandMembers(roomId: string, membershipEvents: MatrixEvent[]): Promise<void> {
+    public setOutOfBandMembers(roomId: string, membershipEvents: IEvent[]): Promise<void> {
         this.oobMembers[roomId] = membershipEvents;
         return Promise.resolve();
     }
diff --git a/src/store/stub.ts b/src/store/stub.ts
index 97ed0165e..f7adb9b3e 100644
--- a/src/store/stub.ts
+++ b/src/store/stub.ts
@@ -23,7 +23,7 @@ import { EventType } from "../@types/event";
 import { Group } from "../models/group";
 import { Room } from "../models/room";
 import { User } from "../models/user";
-import { MatrixEvent } from "../models/event";
+import { IEvent, MatrixEvent } from "../models/event";
 import { Filter } from "../filter";
 import { ISavedSync, IStore } from "./index";
 import { RoomSummary } from "../models/room-summary";
@@ -265,11 +265,11 @@ export class StubStore implements IStore {
         return Promise.resolve();
     }
 
-    public getOutOfBandMembers(): Promise<MatrixEvent[]> {
+    public getOutOfBandMembers(): Promise<IEvent[]> {
         return Promise.resolve(null);
     }
 
-    public setOutOfBandMembers(roomId: string, membershipEvents: MatrixEvent[]): Promise<void> {
+    public setOutOfBandMembers(roomId: string, membershipEvents: IEvent[]): Promise<void> {
         return Promise.resolve();
     }