diff --git a/src/Terms.ts b/src/Terms.ts
index 5a6d96b798..d07555e567 100644
--- a/src/Terms.ts
+++ b/src/Terms.ts
@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import classNames from 'classnames';
+import { SERVICE_TYPES } from 'matrix-js-sdk/src/service-types';
 
 import { MatrixClientPeg } from './MatrixClientPeg';
 import Modal from './Modal';
@@ -32,7 +33,7 @@ export class Service {
      * @param {string} baseUrl The Base URL of the service (ie. before '/_matrix')
      * @param {string} accessToken The user's access token for the service
      */
-    constructor(public serviceType: string, public baseUrl: string, public accessToken: string) {
+    constructor(public serviceType: SERVICE_TYPES, public baseUrl: string, public accessToken: string) {
     }
 }
 
diff --git a/src/components/structures/FilePanel.tsx b/src/components/structures/FilePanel.tsx
index 22a0e1283c..5865201069 100644
--- a/src/components/structures/FilePanel.tsx
+++ b/src/components/structures/FilePanel.tsx
@@ -19,6 +19,7 @@ import React from 'react';
 
 import { Filter } from 'matrix-js-sdk/src/filter';
 import { EventTimelineSet } from "matrix-js-sdk/src/models/event-timeline-set";
+import { Direction } from "matrix-js-sdk/src/models/event-timeline";
 import { MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { TimelineWindow } from 'matrix-js-sdk/src/timeline-window';
@@ -129,7 +130,7 @@ class FilePanel extends React.Component<IProps, IState> {
         }
     }
 
-    public async fetchFileEventsServer(room: Room): Promise<void> {
+    public async fetchFileEventsServer(room: Room): Promise<EventTimelineSet> {
         const client = MatrixClientPeg.get();
 
         const filter = new Filter(client.credentials.userId);
@@ -153,7 +154,11 @@ class FilePanel extends React.Component<IProps, IState> {
         return timelineSet;
     }
 
-    private onPaginationRequest = (timelineWindow: TimelineWindow, direction: string, limit: number): void => {
+    private onPaginationRequest = (
+        timelineWindow: TimelineWindow,
+        direction: Direction,
+        limit: number,
+    ): Promise<boolean> => {
         const client = MatrixClientPeg.get();
         const eventIndex = EventIndexPeg.get();
         const roomId = this.props.roomId;
diff --git a/src/components/structures/TimelinePanel.tsx b/src/components/structures/TimelinePanel.tsx
index 8d5d733082..0b6d33b409 100644
--- a/src/components/structures/TimelinePanel.tsx
+++ b/src/components/structures/TimelinePanel.tsx
@@ -16,11 +16,13 @@ limitations under the License.
 
 import React, { createRef, ReactNode, SyntheticEvent } from 'react';
 import ReactDOM from "react-dom";
-import { Room } from "matrix-js-sdk/src/models/room";
+import { NotificationCountType, Room } from "matrix-js-sdk/src/models/room";
 import { MatrixEvent } from "matrix-js-sdk/src/models/event";
-import { TimelineSet } from "matrix-js-sdk/src/models/event-timeline-set";
-import { EventTimeline } from "matrix-js-sdk/src/models/event-timeline";
+import { EventTimelineSet } from "matrix-js-sdk/src/models/event-timeline-set";
+import { Direction, EventTimeline } from "matrix-js-sdk/src/models/event-timeline";
 import { TimelineWindow } from "matrix-js-sdk/src/timeline-window";
+import { EventType, RelationType } from 'matrix-js-sdk/src/@types/event';
+import { SyncState } from 'matrix-js-sdk/src/sync.api';
 
 import SettingsStore from "../../settings/SettingsStore";
 import { Layout } from "../../settings/Layout";
@@ -39,10 +41,8 @@ import { UIFeature } from "../../settings/UIFeature";
 import { replaceableComponent } from "../../utils/replaceableComponent";
 import { arrayFastClone } from "../../utils/arrays";
 import MessagePanel from "./MessagePanel";
-import { SyncState } from 'matrix-js-sdk/src/sync.api';
 import { IScrollState } from "./ScrollPanel";
 import { ActionPayload } from "../../dispatcher/payloads";
-import { EventType } from 'matrix-js-sdk/src/@types/event';
 import ResizeNotifier from "../../utils/ResizeNotifier";
 import { RoomPermalinkCreator } from "../../utils/permalinks/Permalinks";
 import Spinner from "../views/elements/Spinner";
@@ -65,7 +65,7 @@ interface IProps {
     // representing.  This may or may not have a room, depending on what it's
     // a timeline representing.  If it has a room, we maintain RRs etc for
     // that room.
-    timelineSet: TimelineSet;
+    timelineSet: EventTimelineSet;
     showReadReceipts?: boolean;
     // Enable managing RRs and RMs. These require the timelineSet to have a room.
     manageReadReceipts?: boolean;
@@ -388,7 +388,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
 
     private onPaginationRequest = (
         timelineWindow: TimelineWindow,
-        direction: string,
+        direction: Direction,
         size: number,
     ): Promise<boolean> => {
         if (this.props.onPaginationRequest) {
@@ -579,7 +579,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
         });
     };
 
-    private onRoomTimelineReset = (room: Room, timelineSet: TimelineSet): void => {
+    private onRoomTimelineReset = (room: Room, timelineSet: EventTimelineSet): void => {
         if (timelineSet !== this.props.timelineSet) return;
 
         if (this.messagePanel.current && this.messagePanel.current.isAtBottom()) {
@@ -792,8 +792,8 @@ class TimelinePanel extends React.Component<IProps, IState> {
             // that sending an RR for the latest message will set our notif counter
             // to zero: it may not do this if we send an RR for somewhere before the end.
             if (this.isAtEndOfLiveTimeline()) {
-                this.props.timelineSet.room.setUnreadNotificationCount('total', 0);
-                this.props.timelineSet.room.setUnreadNotificationCount('highlight', 0);
+                this.props.timelineSet.room.setUnreadNotificationCount(NotificationCountType.Total, 0);
+                this.props.timelineSet.room.setUnreadNotificationCount(NotificationCountType.Highlight, 0);
                 dis.dispatch({
                     action: 'on_room_read',
                     roomId: this.props.timelineSet.room.roomId,
@@ -1416,7 +1416,11 @@ class TimelinePanel extends React.Component<IProps, IState> {
         });
     }
 
-    private getRelationsForEvent = (...args) => this.props.timelineSet.getRelationsForEvent(...args);
+    private getRelationsForEvent = (
+        eventId: string,
+        relationType: RelationType,
+        eventType: EventType | string,
+    ) => this.props.timelineSet.getRelationsForEvent(eventId, relationType, eventType);
 
     render() {
         // just show a spinner while the timeline loads.
diff --git a/src/components/views/rooms/SendMessageComposer.tsx b/src/components/views/rooms/SendMessageComposer.tsx
index ec190c829a..2c45c1bbf8 100644
--- a/src/components/views/rooms/SendMessageComposer.tsx
+++ b/src/components/views/rooms/SendMessageComposer.tsx
@@ -17,17 +17,19 @@ limitations under the License.
 import React, { ClipboardEvent, createRef, KeyboardEvent } from 'react';
 import EMOJI_REGEX from 'emojibase-regex';
 import { IContent, MatrixEvent } from 'matrix-js-sdk/src/models/event';
+import { DebouncedFunc, throttle } from 'lodash';
+import { EventType, RelationType } from "matrix-js-sdk/src/@types/event";
 
 import dis from '../../../dispatcher/dispatcher';
 import EditorModel from '../../../editor/model';
 import {
-    htmlSerializeIfNeeded,
-    textSerialize,
     containsEmote,
-    stripEmoteCommand,
-    unescapeMessage,
+    htmlSerializeIfNeeded,
     startsWith,
+    stripEmoteCommand,
     stripPrefix,
+    textSerialize,
+    unescapeMessage,
 } from '../../../editor/serialize';
 import { CommandPartCreator, Part, PartCreator, SerializedPart } from '../../../editor/parts';
 import BasicMessageComposer from "./BasicMessageComposer";
@@ -52,7 +54,6 @@ import { Room } from 'matrix-js-sdk/src/models/room';
 import ErrorDialog from "../dialogs/ErrorDialog";
 import QuestionDialog from "../dialogs/QuestionDialog";
 import { ActionPayload } from "../../../dispatcher/payloads";
-import { DebouncedFunc, throttle } from 'lodash';
 
 function addReplyToMessageContent(
     content: IContent,
@@ -258,12 +259,12 @@ export default class SendMessageComposer extends React.Component<IProps> {
         const events = timeline.getEvents();
         const reaction = this.model.parts[1].text;
         for (let i = events.length - 1; i >= 0; i--) {
-            if (events[i].getType() === "m.room.message") {
+            if (events[i].getType() === EventType.RoomMessage) {
                 let shouldReact = true;
                 const lastMessage = events[i];
                 const userId = MatrixClientPeg.get().getUserId();
                 const messageReactions = this.props.room.getUnfilteredTimelineSet()
-                    .getRelationsForEvent(lastMessage.getId(), "m.annotation", "m.reaction");
+                    .getRelationsForEvent(lastMessage.getId(), RelationType.Annotation, EventType.Reaction);
 
                 // if we have already sent this reaction, don't redact but don't re-send
                 if (messageReactions) {
@@ -274,9 +275,9 @@ export default class SendMessageComposer extends React.Component<IProps> {
                     shouldReact = !myReactionKeys.includes(reaction);
                 }
                 if (shouldReact) {
-                    MatrixClientPeg.get().sendEvent(lastMessage.getRoomId(), "m.reaction", {
+                    MatrixClientPeg.get().sendEvent(lastMessage.getRoomId(), EventType.Reaction, {
                         "m.relates_to": {
-                            "rel_type": "m.annotation",
+                            "rel_type": RelationType.Annotation,
                             "event_id": lastMessage.getId(),
                             "key": reaction,
                         },
diff --git a/src/indexing/EventIndex.ts b/src/indexing/EventIndex.ts
index 43b3de42ed..c84d446197 100644
--- a/src/indexing/EventIndex.ts
+++ b/src/indexing/EventIndex.ts
@@ -16,7 +16,7 @@ limitations under the License.
 
 import { EventEmitter } from "events";
 import { RoomMember } from 'matrix-js-sdk/src/models/room-member';
-import { EventTimeline } from 'matrix-js-sdk/src/models/event-timeline';
+import { Direction, EventTimeline } from 'matrix-js-sdk/src/models/event-timeline';
 import { Room } from 'matrix-js-sdk/src/models/room';
 import { MatrixEvent } from 'matrix-js-sdk/src/models/event';
 import { EventTimelineSet } from 'matrix-js-sdk/src/models/event-timeline-set';
@@ -109,7 +109,7 @@ export default class EventIndex extends EventEmitter {
         // our message crawler.
         await Promise.all(encryptedRooms.map(async (room) => {
             const timeline = room.getLiveTimeline();
-            const token = timeline.getPaginationToken("b");
+            const token = timeline.getPaginationToken(Direction.Backward);
 
             const backCheckpoint: ICrawlerCheckpoint = {
                 roomId: room.roomId,
@@ -371,7 +371,7 @@ export default class EventIndex extends EventEmitter {
         if (!room) return;
 
         const timeline = room.getLiveTimeline();
-        const token = timeline.getPaginationToken("b");
+        const token = timeline.getPaginationToken(Direction.Backward);
 
         if (!token) {
             // The room doesn't contain any tokens, meaning the live timeline
@@ -862,7 +862,7 @@ export default class EventIndex extends EventEmitter {
      * @returns {Promise<boolean>} Resolves to a boolean which is true if more
      * events were successfully retrieved.
      */
-    public paginateTimelineWindow(room: Room, timelineWindow: TimelineWindow, direction: string, limit: number) {
+    public paginateTimelineWindow(room: Room, timelineWindow: TimelineWindow, direction: Direction, limit: number) {
         const tl = timelineWindow.getTimelineIndex(direction);
 
         if (!tl) return Promise.resolve(false);