diff --git a/src/SlashCommands.js b/src/SlashCommands.tsx
similarity index 91%
rename from src/SlashCommands.js
rename to src/SlashCommands.tsx
index d306978f78..e69afbde48 100644
--- a/src/SlashCommands.js
+++ b/src/SlashCommands.tsx
@@ -2,6 +2,7 @@
 Copyright 2015, 2016 OpenMarket Ltd
 Copyright 2018 New Vector Ltd
 Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
+Copyright 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.
@@ -17,7 +18,8 @@ limitations under the License.
 */
 
 
-import React from 'react';
+import * as React from 'react';
+
 import {MatrixClientPeg} from './MatrixClientPeg';
 import dis from './dispatcher';
 import * as sdk from './index';
@@ -34,11 +36,16 @@ import { getDefaultIdentityServerUrl, useDefaultIdentityServer } from './utils/I
 import {isPermalinkHost, parsePermalink} from "./utils/permalinks/Permalinks";
 import {inviteUsersToRoom} from "./RoomInvite";
 
-const singleMxcUpload = async () => {
+// XXX: workaround for https://github.com/microsoft/TypeScript/issues/31816
+interface HTMLInputEvent extends Event {
+    target: HTMLInputElement & EventTarget;
+}
+
+const singleMxcUpload = async (): Promise<any> => {
     return new Promise((resolve) => {
         const fileSelector = document.createElement('input');
         fileSelector.setAttribute('type', 'file');
-        fileSelector.onchange = (ev) => {
+        fileSelector.onchange = (ev: HTMLInputEvent) => {
             const file = ev.target.files[0];
 
             const UploadConfirmDialog = sdk.getComponent("dialogs.UploadConfirmDialog");
@@ -62,9 +69,36 @@ export const CommandCategories = {
     "other": _td("Other"),
 };
 
+type RunFn = ((roomId: string, args: string, cmd: string) => {error: any} | {promise: Promise<any>});
+
 class Command {
-    constructor({name, args='', description, runFn, category=CommandCategories.other, hideCompletionAfterSpace=false}) {
-        this.command = '/' + name;
+    command: string;
+    aliases: string[];
+    args: undefined | string;
+    description: string;
+    runFn: undefined | RunFn;
+    category: string;
+    hideCompletionAfterSpace: boolean;
+
+    constructor({
+        command,
+        aliases=[],
+        args='',
+        description,
+        runFn=undefined,
+        category=CommandCategories.other,
+        hideCompletionAfterSpace=false,
+    }: {
+        command: string;
+        aliases?: string[];
+        args?: string;
+        description: string;
+        runFn?: RunFn;
+        category: string;
+        hideCompletionAfterSpace?: boolean;
+    }) {
+        this.command = command;
+        this.aliases = aliases;
         this.args = args;
         this.description = description;
         this.runFn = runFn;
@@ -73,17 +107,17 @@ class Command {
     }
 
     getCommand() {
-        return this.command;
+        return `/${this.command}`;
     }
 
     getCommandWithArgs() {
         return this.getCommand() + " " + this.args;
     }
 
-    run(roomId, args) {
+    run(roomId: string, args: string, cmd: string) {
         // if it has no runFn then its an ignored/nop command (autocomplete only) e.g `/me`
         if (!this.runFn) return;
-        return this.runFn.bind(this)(roomId, args);
+        return this.runFn.bind(this)(roomId, args, cmd);
     }
 
     getUsage() {
@@ -95,7 +129,7 @@ function reject(error) {
     return {error};
 }
 
-function success(promise) {
+function success(promise?: Promise<any>) {
     return {promise};
 }
 
@@ -103,11 +137,9 @@ function success(promise) {
  * functions are called with `this` bound to the Command instance.
  */
 
-/* eslint-disable babel/no-invalid-this */
-
-export const CommandMap = {
-    shrug: new Command({
-        name: 'shrug',
+export const Commands = [
+    new Command({
+        command: 'shrug',
         args: '<message>',
         description: _td('Prepends ¯\\_(ツ)_/¯ to a plain-text message'),
         runFn: function(roomId, args) {
@@ -119,8 +151,8 @@ export const CommandMap = {
         },
         category: CommandCategories.messages,
     }),
-    plain: new Command({
-        name: 'plain',
+    new Command({
+        command: 'plain',
         args: '<message>',
         description: _td('Sends a message as plain text, without interpreting it as markdown'),
         runFn: function(roomId, messages) {
@@ -128,11 +160,11 @@ export const CommandMap = {
         },
         category: CommandCategories.messages,
     }),
-    ddg: new Command({
-        name: 'ddg',
+    new Command({
+        command: 'ddg',
         args: '<query>',
         description: _td('Searches DuckDuckGo for results'),
-        runFn: function(roomId, args) {
+        runFn: function() {
             const ErrorDialog = sdk.getComponent('dialogs.ErrorDialog');
             // TODO Don't explain this away, actually show a search UI here.
             Modal.createTrackedDialog('Slash Commands', '/ddg is not a command', ErrorDialog, {
@@ -144,9 +176,8 @@ export const CommandMap = {
         category: CommandCategories.actions,
         hideCompletionAfterSpace: true,
     }),
-
-    upgraderoom: new Command({
-        name: 'upgraderoom',
+    new Command({
+        command: 'upgraderoom',
         args: '<new_version>',
         description: _td('Upgrades a room to a new version'),
         runFn: function(roomId, args) {
@@ -215,9 +246,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    nick: new Command({
-        name: 'nick',
+    new Command({
+        command: 'nick',
         args: '<display_name>',
         description: _td('Changes your display nickname'),
         runFn: function(roomId, args) {
@@ -228,9 +258,9 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    myroomnick: new Command({
-        name: 'myroomnick',
+    new Command({
+        command: 'myroomnick',
+        aliases: ['roomnick'],
         args: '<display_name>',
         description: _td('Changes your display nickname in the current room only'),
         runFn: function(roomId, args) {
@@ -239,7 +269,7 @@ export const CommandMap = {
                 const ev = cli.getRoom(roomId).currentState.getStateEvents('m.room.member', cli.getUserId());
                 const content = {
                     ...ev ? ev.getContent() : { membership: 'join' },
-                    displayname: args,
+                    displaycommand: args,
                 };
                 return success(cli.sendStateEvent(roomId, 'm.room.member', content, cli.getUserId()));
             }
@@ -247,9 +277,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    roomavatar: new Command({
-        name: 'roomavatar',
+    new Command({
+        command: 'roomavatar',
         args: '[<mxc_url>]',
         description: _td('Changes the avatar of the current room'),
         runFn: function(roomId, args) {
@@ -265,9 +294,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    myroomavatar: new Command({
-        name: 'myroomavatar',
+    new Command({
+        command: 'myroomavatar',
         args: '[<mxc_url>]',
         description: _td('Changes your avatar in this current room only'),
         runFn: function(roomId, args) {
@@ -292,9 +320,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    myavatar: new Command({
-        name: 'myavatar',
+    new Command({
+        command: 'myavatar',
         args: '[<mxc_url>]',
         description: _td('Changes your avatar in all rooms'),
         runFn: function(roomId, args) {
@@ -310,9 +337,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    topic: new Command({
-        name: 'topic',
+    new Command({
+        command: 'topic',
         args: '[<topic>]',
         description: _td('Gets or sets the room topic'),
         runFn: function(roomId, args) {
@@ -336,9 +362,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    roomname: new Command({
-        name: 'roomname',
+    new Command({
+        command: 'roomname',
         args: '<name>',
         description: _td('Sets the room name'),
         runFn: function(roomId, args) {
@@ -349,9 +374,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    invite: new Command({
-        name: 'invite',
+    new Command({
+        command: 'invite',
         args: '<user-id>',
         description: _td('Invites user with given id to current room'),
         runFn: function(roomId, args) {
@@ -390,7 +414,7 @@ export const CommandMap = {
                         }
                     }
                     const inviter = new MultiInviter(roomId);
-                    return success(finished.then(([useDefault] = []) => {
+                    return success(finished.then(([useDefault]: any) => {
                         if (useDefault) {
                             useDefaultIdentityServer();
                         } else if (useDefault === false) {
@@ -408,9 +432,9 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    join: new Command({
-        name: 'join',
+    new Command({
+        command: 'join',
+        aliases: ['j', 'goto'],
         args: '<room-alias>',
         description: _td('Joins room with given alias'),
         runFn: function(roomId, args) {
@@ -521,9 +545,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    part: new Command({
-        name: 'part',
+    new Command({
+        command: 'part',
         args: '[<room-alias>]',
         description: _td('Leave room'),
         runFn: function(roomId, args) {
@@ -569,9 +592,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    kick: new Command({
-        name: 'kick',
+    new Command({
+        command: 'kick',
         args: '<user-id> [reason]',
         description: _td('Kicks user with given id'),
         runFn: function(roomId, args) {
@@ -585,10 +607,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    // Ban a user from the room with an optional reason
-    ban: new Command({
-        name: 'ban',
+    new Command({
+        command: 'ban',
         args: '<user-id> [reason]',
         description: _td('Bans user with given id'),
         runFn: function(roomId, args) {
@@ -602,10 +622,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    // Unban a user from ythe room
-    unban: new Command({
-        name: 'unban',
+    new Command({
+        command: 'unban',
         args: '<user-id>',
         description: _td('Unbans user with given ID'),
         runFn: function(roomId, args) {
@@ -620,9 +638,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    ignore: new Command({
-        name: 'ignore',
+    new Command({
+        command: 'ignore',
         args: '<user-id>',
         description: _td('Ignores a user, hiding their messages from you'),
         runFn: function(roomId, args) {
@@ -651,9 +668,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    unignore: new Command({
-        name: 'unignore',
+    new Command({
+        command: 'unignore',
         args: '<user-id>',
         description: _td('Stops ignoring a user, showing their messages going forward'),
         runFn: function(roomId, args) {
@@ -683,10 +699,8 @@ export const CommandMap = {
         },
         category: CommandCategories.actions,
     }),
-
-    // Define the power level of a user
-    op: new Command({
-        name: 'op',
+    new Command({
+        command: 'op',
         args: '<user-id> [<power-level>]',
         description: _td('Define the power level of a user'),
         runFn: function(roomId, args) {
@@ -712,10 +726,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    // Reset the power level of a user
-    deop: new Command({
-        name: 'deop',
+    new Command({
+        command: 'deop',
         args: '<user-id>',
         description: _td('Deops user with given id'),
         runFn: function(roomId, args) {
@@ -734,9 +746,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    devtools: new Command({
-        name: 'devtools',
+    new Command({
+        command: 'devtools',
         description: _td('Opens the Developer Tools dialog'),
         runFn: function(roomId) {
             const DevtoolsDialog = sdk.getComponent('dialogs.DevtoolsDialog');
@@ -745,9 +756,8 @@ export const CommandMap = {
         },
         category: CommandCategories.advanced,
     }),
-
-    addwidget: new Command({
-        name: 'addwidget',
+    new Command({
+        command: 'addwidget',
         args: '<url>',
         description: _td('Adds a custom widget by URL to the room'),
         runFn: function(roomId, args) {
@@ -766,10 +776,8 @@ export const CommandMap = {
         },
         category: CommandCategories.admin,
     }),
-
-    // Verify a user, device, and pubkey tuple
-    verify: new Command({
-        name: 'verify',
+    new Command({
+        command: 'verify',
         args: '<user-id> <device-id> <device-signing-key>',
         description: _td('Verifies a user, session, and pubkey tuple'),
         runFn: function(roomId, args) {
@@ -834,20 +842,9 @@ export const CommandMap = {
         },
         category: CommandCategories.advanced,
     }),
-
-    // Command definitions for autocompletion ONLY:
-
-    // /me is special because its not handled by SlashCommands.js and is instead done inside the Composer classes
-    me: new Command({
-        name: 'me',
-        args: '<message>',
-        description: _td('Displays action'),
-        category: CommandCategories.messages,
-        hideCompletionAfterSpace: true,
-    }),
-
-    discardsession: new Command({
-        name: 'discardsession',
+    new Command({
+        command: 'discardsession',
+        aliases: ['newballsplease'],
         description: _td('Forces the current outbound group session in an encrypted room to be discarded'),
         runFn: function(roomId) {
             try {
@@ -859,9 +856,8 @@ export const CommandMap = {
         },
         category: CommandCategories.advanced,
     }),
-
-    rainbow: new Command({
-        name: "rainbow",
+    new Command({
+        command: "rainbow",
         description: _td("Sends the given message coloured as a rainbow"),
         args: '<message>',
         runFn: function(roomId, args) {
@@ -870,9 +866,8 @@ export const CommandMap = {
         },
         category: CommandCategories.messages,
     }),
-
-    rainbowme: new Command({
-        name: "rainbowme",
+    new Command({
+        command: "rainbowme",
         description: _td("Sends the given emote coloured as a rainbow"),
         args: '<message>',
         runFn: function(roomId, args) {
@@ -881,9 +876,8 @@ export const CommandMap = {
         },
         category: CommandCategories.messages,
     }),
-
-    help: new Command({
-        name: "help",
+    new Command({
+        command: "help",
         description: _td("Displays list of commands with usages and descriptions"),
         runFn: function() {
             const SlashCommandHelpDialog = sdk.getComponent('dialogs.SlashCommandHelpDialog');
@@ -894,36 +888,25 @@ export const CommandMap = {
         category: CommandCategories.advanced,
     }),
 
-    whois: new Command({
-        name: "whois",
-        description: _td("Displays information about a user"),
-        args: '<user-id>',
-        runFn: function(roomId, userId) {
-            if (!userId || !userId.startsWith("@") || !userId.includes(":")) {
-                return reject(this.getUsage());
-            }
-
-            const member = MatrixClientPeg.get().getRoom(roomId).getMember(userId);
-
-            dis.dispatch({
-                action: 'view_user',
-                member: member || {userId},
-            });
-            return success();
-        },
-        category: CommandCategories.advanced,
+    // Command definitions for autocompletion ONLY:
+    // /me is special because its not handled by SlashCommands.js and is instead done inside the Composer classes
+    new Command({
+        command: 'me',
+        args: '<message>',
+        description: _td('Displays action'),
+        category: CommandCategories.messages,
+        hideCompletionAfterSpace: true,
     }),
-};
-/* eslint-enable babel/no-invalid-this */
+];
 
-
-// helpful aliases
-const aliases = {
-    j: "join",
-    newballsplease: "discardsession",
-    goto: "join", // because it handles event permalinks magically
-    roomnick: "myroomnick",
-};
+// build a map from names and aliases to the Command objects.
+export const CommandMap = new Map();
+Commands.forEach(cmd => {
+    CommandMap.set(cmd.command, cmd);
+    cmd.aliases.forEach(alias => {
+        CommandMap.set(alias, cmd);
+    });
+});
 
 
 /**
@@ -950,10 +933,7 @@ export function getCommand(roomId, input) {
         cmd = input;
     }
 
-    if (aliases[cmd]) {
-        cmd = aliases[cmd];
-    }
-    if (CommandMap[cmd]) {
-        return () => CommandMap[cmd].run(roomId, args);
+    if (CommandMap.has(cmd)) {
+        return () => CommandMap.get(cmd).run(roomId, args, cmd);
     }
 }
diff --git a/src/autocomplete/CommandProvider.js b/src/autocomplete/CommandProvider.js
index da8fa3ed3c..0b8af4d6f9 100644
--- a/src/autocomplete/CommandProvider.js
+++ b/src/autocomplete/CommandProvider.js
@@ -23,17 +23,16 @@ import AutocompleteProvider from './AutocompleteProvider';
 import QueryMatcher from './QueryMatcher';
 import {TextualCompletion} from './Components';
 import type {Completion, SelectionRange} from "./Autocompleter";
-import {CommandMap} from '../SlashCommands';
-
-const COMMANDS = Object.values(CommandMap);
+import {Commands, CommandMap} from '../SlashCommands';
 
 const COMMAND_RE = /(^\/\w*)(?: .*)?/g;
 
 export default class CommandProvider extends AutocompleteProvider {
     constructor() {
         super(COMMAND_RE);
-        this.matcher = new QueryMatcher(COMMANDS, {
-           keys: ['command', 'args', 'description'],
+        this.matcher = new QueryMatcher(Commands, {
+            keys: ['command', 'args', 'description'],
+            funcs: [({aliases}) => aliases.join(" ")], // aliases
         });
     }
 
@@ -46,31 +45,40 @@ export default class CommandProvider extends AutocompleteProvider {
         if (command[0] !== command[1]) {
             // The input looks like a command with arguments, perform exact match
             const name = command[1].substr(1); // strip leading `/`
-            if (CommandMap[name]) {
+            if (CommandMap.has(name)) {
                 // some commands, namely `me` and `ddg` don't suit having the usage shown whilst typing their arguments
-                if (CommandMap[name].hideCompletionAfterSpace) return [];
-                matches = [CommandMap[name]];
+                if (CommandMap.get(name).hideCompletionAfterSpace) return [];
+                matches = [CommandMap.get(name)];
             }
         } else {
             if (query === '/') {
                 // If they have just entered `/` show everything
-                matches = COMMANDS;
+                matches = Commands;
             } else {
                 // otherwise fuzzy match against all of the fields
                 matches = this.matcher.match(command[1]);
             }
         }
 
-        return matches.map((result) => ({
-            // If the command is the same as the one they entered, we don't want to discard their arguments
-            completion: result.command === command[1] ? command[0] : (result.command + ' '),
-            type: "command",
-            component: <TextualCompletion
-                title={result.command}
-                subtitle={result.args}
-                description={_t(result.description)} />,
-            range,
-        }));
+
+        return matches.map((result) => {
+            let completion = result.getCommand() + ' ';
+            const usedAlias = result.aliases.find(alias => `/${alias}` === command[1]);
+            // If the command (or an alias) is the same as the one they entered, we don't want to discard their arguments
+            if (usedAlias || result.getCommand() === command[1]) {
+                completion = command[0];
+            }
+
+            return {
+                completion,
+                type: "command",
+                component: <TextualCompletion
+                    title={`/${usedAlias || result.command}`}
+                    subtitle={result.args}
+                    description={_t(result.description)} />,
+                range,
+            };
+        });
     }
 
     getName() {
diff --git a/src/components/views/dialogs/SlashCommandHelpDialog.js b/src/components/views/dialogs/SlashCommandHelpDialog.js
index 9e48a92ed1..bae5b37993 100644
--- a/src/components/views/dialogs/SlashCommandHelpDialog.js
+++ b/src/components/views/dialogs/SlashCommandHelpDialog.js
@@ -16,14 +16,14 @@ limitations under the License.
 
 import React from 'react';
 import {_t} from "../../../languageHandler";
-import {CommandCategories, CommandMap} from "../../../SlashCommands";
+import {CommandCategories, Commands} from "../../../SlashCommands";
 import * as sdk from "../../../index";
 
 export default ({onFinished}) => {
     const InfoDialog = sdk.getComponent('dialogs.InfoDialog');
 
     const categories = {};
-    Object.values(CommandMap).forEach(cmd => {
+    Commands.forEach(cmd => {
         if (!categories[cmd.category]) {
             categories[cmd.category] = [];
         }
@@ -41,7 +41,7 @@ export default ({onFinished}) => {
 
         categories[category].forEach(cmd => {
             rows.push(<tr key={cmd.command}>
-                <td><strong>{cmd.command}</strong></td>
+                <td><strong>{cmd.getCommand()}</strong></td>
                 <td>{cmd.args}</td>
                 <td>{cmd.description}</td>
             </tr>);