diff --git a/src/Browser.ts b/src/Browser.ts
index 5ac2fec581d..10f7e7279a9 100644
--- a/src/Browser.ts
+++ b/src/Browser.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-import { helper, assert } from './helper';
+import { assert } from './assert';
+import { helper } from './helper';
 import { Target } from './Target';
 import { EventEmitter } from './EventEmitter';
 import { Events } from './Events';
diff --git a/src/BrowserFetcher.ts b/src/BrowserFetcher.ts
index 4eacc6e7eef..3fd2d72dc9a 100644
--- a/src/BrowserFetcher.ts
+++ b/src/BrowserFetcher.ts
@@ -28,8 +28,8 @@ import removeRecursive from 'rimraf';
 import * as URL from 'url';
 import ProxyAgent from 'https-proxy-agent';
 import { getProxyForUrl } from 'proxy-from-env';
-
-import { helper, assert } from './helper';
+import { assert } from './assert';
+import { helper } from './helper';
 const debugFetcher = debug(`puppeteer:fetcher`);
 
 const downloadURLs = {
diff --git a/src/Connection.ts b/src/Connection.ts
index 2ff5a75476f..a2b28fa97fe 100644
--- a/src/Connection.ts
+++ b/src/Connection.ts
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { assert } from './helper';
+import { assert } from './assert';
 import { Events } from './Events';
 import debug from 'debug';
 const debugProtocolSend = debug('puppeteer:protocol:SEND ►');
diff --git a/src/Coverage.ts b/src/Coverage.ts
index 0d90c5e7c3d..5f8bff84630 100644
--- a/src/Coverage.ts
+++ b/src/Coverage.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-import { helper, debugError, assert, PuppeteerEventListener } from './helper';
+import { assert } from './assert';
+import { helper, debugError, PuppeteerEventListener } from './helper';
 import Protocol from './protocol';
 import { CDPSession } from './Connection';
 
diff --git a/src/DOMWorld.ts b/src/DOMWorld.ts
index cc30a458b08..678ddc4300d 100644
--- a/src/DOMWorld.ts
+++ b/src/DOMWorld.ts
@@ -15,7 +15,8 @@
  */
 
 import * as fs from 'fs';
-import { helper, assert } from './helper';
+import { assert } from './assert';
+import { helper } from './helper';
 import { LifecycleWatcher, PuppeteerLifeCycleEvent } from './LifecycleWatcher';
 import { TimeoutError } from './Errors';
 import { JSHandle, ElementHandle } from './JSHandle';
diff --git a/src/Dialog.ts b/src/Dialog.ts
index 716c467c2e8..775d10dbb1c 100644
--- a/src/Dialog.ts
+++ b/src/Dialog.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { assert } from './helper';
+import { assert } from './assert';
 import { CDPSession } from './Connection';
 import Protocol from './protocol';
 
diff --git a/src/ExecutionContext.ts b/src/ExecutionContext.ts
index c82ad8443d7..32db1a0c906 100644
--- a/src/ExecutionContext.ts
+++ b/src/ExecutionContext.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-import { helper, assert } from './helper';
+import { assert } from './assert';
+import { helper } from './helper';
 import { createJSHandle, JSHandle, ElementHandle } from './JSHandle';
 import { CDPSession } from './Connection';
 import { DOMWorld } from './DOMWorld';
diff --git a/src/FileChooser.ts b/src/FileChooser.ts
index ed6303451c4..99a2b142812 100644
--- a/src/FileChooser.ts
+++ b/src/FileChooser.ts
@@ -16,7 +16,7 @@
 
 import { ElementHandle } from './JSHandle';
 import Protocol from './protocol';
-import { assert } from './helper';
+import { assert } from './assert';
 
 export class FileChooser {
   private _element: ElementHandle;
diff --git a/src/FrameManager.ts b/src/FrameManager.ts
index d16ab3698ac..3ac37085ba7 100644
--- a/src/FrameManager.ts
+++ b/src/FrameManager.ts
@@ -15,7 +15,8 @@
  */
 
 import { EventEmitter } from './EventEmitter';
-import { helper, assert, debugError } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import { Events } from './Events';
 import { ExecutionContext, EVALUATION_SCRIPT_URL } from './ExecutionContext';
 import { LifecycleWatcher, PuppeteerLifeCycleEvent } from './LifecycleWatcher';
diff --git a/src/HTTPRequest.ts b/src/HTTPRequest.ts
index b8ed5057800..7df17ee24ee 100644
--- a/src/HTTPRequest.ts
+++ b/src/HTTPRequest.ts
@@ -16,7 +16,8 @@
 import { CDPSession } from './Connection';
 import { Frame } from './FrameManager';
 import { HTTPResponse } from './HTTPResponse';
-import { helper, assert, debugError } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import Protocol from './protocol';
 
 export class HTTPRequest {
diff --git a/src/Input.ts b/src/Input.ts
index 0fef07d2933..7a49b224b12 100644
--- a/src/Input.ts
+++ b/src/Input.ts
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-import { assert } from './helper';
+import { assert } from './assert';
 import { CDPSession } from './Connection';
 import { keyDefinitions, KeyDefinition, KeyInput } from './USKeyboardLayout';
 
diff --git a/src/JSHandle.ts b/src/JSHandle.ts
index d8be11c637f..38e814eea84 100644
--- a/src/JSHandle.ts
+++ b/src/JSHandle.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-import { helper, assert, debugError } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import { ExecutionContext } from './ExecutionContext';
 import { Page } from './Page';
 import { CDPSession } from './Connection';
diff --git a/src/Launcher.ts b/src/Launcher.ts
index 0a0e9f7cf14..60e977cdc3a 100644
--- a/src/Launcher.ts
+++ b/src/Launcher.ts
@@ -23,7 +23,8 @@ import * as fs from 'fs';
 import { BrowserFetcher } from './BrowserFetcher';
 import { Connection } from './Connection';
 import { Browser } from './Browser';
-import { helper, assert, debugError } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import { ConnectionTransport } from './ConnectionTransport';
 import { WebSocketTransport } from './WebSocketTransport';
 import { BrowserRunner } from './launcher/BrowserRunner';
diff --git a/src/LifecycleWatcher.ts b/src/LifecycleWatcher.ts
index 775453374c7..7f400911f1e 100644
--- a/src/LifecycleWatcher.ts
+++ b/src/LifecycleWatcher.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-import { helper, assert, PuppeteerEventListener } from './helper';
+import { assert } from './assert';
+import { helper, PuppeteerEventListener } from './helper';
 import { Events } from './Events';
 import { TimeoutError } from './Errors';
 import { FrameManager, Frame } from './FrameManager';
diff --git a/src/NetworkManager.ts b/src/NetworkManager.ts
index 8043744f611..46ed595ba81 100644
--- a/src/NetworkManager.ts
+++ b/src/NetworkManager.ts
@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 import { EventEmitter } from './EventEmitter';
-import { helper, assert, debugError } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import Protocol from './protocol';
 import { Events } from './Events';
 import { CDPSession } from './Connection';
diff --git a/src/Page.ts b/src/Page.ts
index be1a593df63..c5f51179e80 100644
--- a/src/Page.ts
+++ b/src/Page.ts
@@ -24,7 +24,8 @@ import { EmulationManager } from './EmulationManager';
 import { Frame, FrameManager } from './FrameManager';
 import { Keyboard, Mouse, Touchscreen, MouseButtonInput } from './Input';
 import { Tracing } from './Tracing';
-import { helper, debugError, assert } from './helper';
+import { assert } from './assert';
+import { helper, debugError } from './helper';
 import { Coverage } from './Coverage';
 import { WebWorker } from './WebWorker';
 import { Browser, BrowserContext } from './Browser';
diff --git a/src/Tracing.ts b/src/Tracing.ts
index 8f19840a54a..5f2c4a4880a 100644
--- a/src/Tracing.ts
+++ b/src/Tracing.ts
@@ -13,7 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { helper, assert } from './helper';
+import { assert } from './assert';
+import { helper } from './helper';
 import { CDPSession } from './Connection';
 
 interface TracingOptions {
diff --git a/src/assert.ts b/src/assert.ts
new file mode 100644
index 00000000000..6ba090ce26e
--- /dev/null
+++ b/src/assert.ts
@@ -0,0 +1,24 @@
+/**
+ * Copyright 2020 Google Inc. All rights reserved.
+ *
+ * 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.
+ */
+
+/**
+ * Asserts that the given value is truthy.
+ * @param value
+ * @param message - the error message to throw if the value is not truthy.
+ */
+export const assert = (value: unknown, message?: string): void => {
+  if (!value) throw new Error(message);
+};
diff --git a/src/helper.ts b/src/helper.ts
index c1103e9104f..03b4a8c6343 100644
--- a/src/helper.ts
+++ b/src/helper.ts
@@ -20,6 +20,7 @@ import { CDPSession } from './Connection';
 import { promisify } from 'util';
 import Protocol from './protocol';
 import { CommonEventEmitter } from './EventEmitter';
+import { assert } from './assert';
 
 const openAsync = promisify(fs.open);
 const writeAsync = promisify(fs.write);
@@ -27,10 +28,6 @@ const closeAsync = promisify(fs.close);
 
 export const debugError = debug('puppeteer:error');
 
-export function assert(value: unknown, message?: string): void {
-  if (!value) throw new Error(message);
-}
-
 interface AnyClass {
   prototype: object;
 }
diff --git a/src/launcher/BrowserRunner.ts b/src/launcher/BrowserRunner.ts
index 7b571cabb26..03ea2becbc7 100644
--- a/src/launcher/BrowserRunner.ts
+++ b/src/launcher/BrowserRunner.ts
@@ -18,7 +18,8 @@ import debug from 'debug';
 
 import removeFolder from 'rimraf';
 import * as childProcess from 'child_process';
-import { helper, assert, debugError } from '../helper';
+import { assert } from '../assert';
+import { helper, debugError } from '../helper';
 import { LaunchOptions } from './LaunchOptions';
 import { Connection } from '../Connection';
 import { WebSocketTransport } from '../WebSocketTransport';