diff --git a/src/Modal.js b/src/Modal.js
index cb19731f01..26c9da8bbb 100644
--- a/src/Modal.js
+++ b/src/Modal.js
@@ -24,7 +24,6 @@ import sdk from './index';
 import dis from './dispatcher';
 import { _t } from './languageHandler';
 import Promise from "bluebird";
-import {defer} from "./utils/promise";
 
 const DIALOG_CONTAINER_ID = "mx_Dialog_Container";
 const STATIC_DIALOG_CONTAINER_ID = "mx_Dialog_StaticContainer";
@@ -203,7 +202,7 @@ class ModalManager {
     }
 
     _getCloseFn(modal, props) {
-        const deferred = defer();
+        const deferred = Promise.defer();
         return [(...args) => {
             deferred.resolve(args);
             if (props && props.onFinished) props.onFinished.apply(null, args);
diff --git a/src/components/structures/MatrixChat.js b/src/components/structures/MatrixChat.js
index d12eba88f7..da67416400 100644
--- a/src/components/structures/MatrixChat.js
+++ b/src/components/structures/MatrixChat.js
@@ -60,7 +60,6 @@ import AutoDiscoveryUtils from "../../utils/AutoDiscoveryUtils";
 import DMRoomMap from '../../utils/DMRoomMap';
 import { countRoomsWithNotif } from '../../RoomNotifs';
 import { setTheme } from "../../theme";
-import {defer} from "../../utils/promise";
 
 // Disable warnings for now: we use deprecated bluebird functions
 // and need to migrate, but they spam the console with warnings.
@@ -237,7 +236,7 @@ export default createReactClass({
 
         // Used by _viewRoom before getting state from sync
         this.firstSyncComplete = false;
-        this.firstSyncPromise = defer();
+        this.firstSyncPromise = Promise.defer();
 
         if (this.props.config.sync_timeline_limit) {
             MatrixClientPeg.opts.initialSyncLimit = this.props.config.sync_timeline_limit;
@@ -1262,7 +1261,7 @@ export default createReactClass({
         // since we're about to start the client and therefore about
         // to do the first sync
         this.firstSyncComplete = false;
-        this.firstSyncPromise = defer();
+        this.firstSyncPromise = Promise.defer();
         const cli = MatrixClientPeg.get();
         const IncomingSasDialog = sdk.getComponent('views.dialogs.IncomingSasDialog');
 
diff --git a/src/utils/MultiInviter.js b/src/utils/MultiInviter.js
index de5c2e7610..e8995b46d7 100644
--- a/src/utils/MultiInviter.js
+++ b/src/utils/MultiInviter.js
@@ -24,7 +24,6 @@ import {_t} from "../languageHandler";
 import sdk from "../index";
 import Modal from "../Modal";
 import SettingsStore from "../settings/SettingsStore";
-import {defer} from "./promise";
 
 /**
  * Invites multiple addresses to a room or group, handling rate limiting from the server
@@ -72,7 +71,7 @@ export default class MultiInviter {
                 };
             }
         }
-        this.deferred = defer();
+        this.deferred = Promise.defer();
         this._inviteMore(0);
 
         return this.deferred.promise;
diff --git a/src/utils/promise.js b/src/utils/promise.js
deleted file mode 100644
index dd10f7fdd7..0000000000
--- a/src/utils/promise.js
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
-Copyright 2019 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.
-*/
-
-// @flow
-
-// Returns a promise which resolves with a given value after the given number of ms
-export const sleep = (ms: number, value: any): Promise => new Promise((resolve => { setTimeout(resolve, ms, value); }));
-
-// Returns a promise which resolves when the input promise resolves with its value
-// or when the timeout of ms is reached with the value of given timeoutValue
-export async function timeout(promise: Promise, timeoutValue: any, ms: number): Promise {
-    const timeoutPromise = new Promise((resolve) => {
-        const timeoutId = setTimeout(resolve, ms, timeoutValue);
-        promise.then(() => {
-            clearTimeout(timeoutId);
-        });
-    });
-
-    return Promise.race([promise, timeoutPromise]);
-}
-
-// Returns a Deferred
-export function defer(): {resolve: () => {}, reject: () => {}, promise: Promise} {
-    let resolve;
-    let reject;
-
-    const promise = new Promise((_resolve, _reject) => {
-        resolve = _resolve;
-        reject = _reject;
-    });
-
-    return {resolve, reject, promise};
-}