diff --git a/src/display/api.js b/src/display/api.js
index dd0052bdb..bdec3bf94 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -16,9 +16,10 @@
 
 import {
   assert, createPromiseCapability, getVerbosityLevel, info, InvalidPDFException,
-  isArrayBuffer, isSameOrigin, MessageHandler, MissingPDFException,
-  NativeImageDecoding, PageViewport, PasswordException, stringToBytes,
-  UnexpectedResponseException, UnknownErrorException, unreachable, Util, warn
+  isArrayBuffer, isNum, isSameOrigin, MessageHandler, MissingPDFException,
+  NativeImageDecoding, PageViewport, PasswordException, setVerbosityLevel,
+  stringToBytes, UnexpectedResponseException, UnknownErrorException,
+  unreachable, Util, warn
 } from '../shared/util';
 import {
   DOMCanvasFactory, DOMCMapReaderFactory, DummyStatTimer, getDefaultSetting,
@@ -128,6 +129,8 @@ function setPDFNetworkStreamFactory(pdfNetworkStreamFactory) {
  *   the loading and parsing of the PDF data.
  * @property {boolean} postMessageTransfers - (optional) Enables transfer usage
  *   in postMessage for ArrayBuffers. The default value is `true`.
+ * @property {number} verbosity - (optional) Controls the logging level; the
+ *   constants from {VerbosityLevel} should be used.
  * @property {string} docBaseUrl - (optional) The base URL of the document,
  *   used when attempting to recover valid absolute URLs for annotations, and
  *   outline items, that (incorrectly) only specify relative URLs.
@@ -240,9 +243,13 @@ function getDocument(src) {
     params.nativeImageDecoderSupport = NativeImageDecoding.DECODE;
   }
 
+  // Set the main-thread verbosity level.
+  setVerbosityLevel(params.verbosity);
+
   if (!worker) {
     const workerParams = {
       postMessageTransfers: params.postMessageTransfers,
+      verbosity: params.verbosity,
     };
     // Worker was not provided -- creating and owning our own. If message port
     // is specified in global worker options, using it.
@@ -1206,6 +1213,8 @@ class LoopbackPort {
  * @property {Object} port - (optional) The `workerPort`.
  * @property {boolean} postMessageTransfers - (optional) Enables transfer usage
  *   in postMessage for ArrayBuffers. The default value is `true`.
+ * @property {number} verbosity - (optional) Controls the logging level; the
+ *   constants from {VerbosityLevel} should be used.
  */
 
 /**
@@ -1300,7 +1309,7 @@ var PDFWorker = (function PDFWorkerClosure() {
    * @param {PDFWorkerParameters} params - The worker initialization parameters.
    */
   function PDFWorker({ name = null, port = null,
-                       postMessageTransfers = true, } = {}) {
+                       postMessageTransfers = true, verbosity = null, } = {}) {
     if (port && pdfWorkerPorts.has(port)) {
       throw new Error('Cannot use more than one PDFWorker per port');
     }
@@ -1308,6 +1317,7 @@ var PDFWorker = (function PDFWorkerClosure() {
     this.name = name;
     this.destroyed = false;
     this.postMessageTransfers = postMessageTransfers !== false;
+    this.verbosity = (isNum(verbosity) ? verbosity : getVerbosityLevel());
 
     this._readyCapability = createPromiseCapability();
     this._port = null;
@@ -1408,7 +1418,7 @@ var PDFWorker = (function PDFWorkerClosure() {
               this._readyCapability.resolve();
               // Send global setting, e.g. verbosity level.
               messageHandler.send('configure', {
-                verbosity: getVerbosityLevel(),
+                verbosity: this.verbosity,
               });
             } else {
               this._setupFakeWorker();
diff --git a/src/display/global.js b/src/display/global.js
index 5a087f02f..c4b329fdc 100644
--- a/src/display/global.js
+++ b/src/display/global.js
@@ -14,11 +14,10 @@
  */
 
 import {
-  createBlob, createObjectURL, createPromiseCapability, getVerbosityLevel,
-  InvalidPDFException, isLittleEndian, MissingPDFException, OPS, PageViewport,
-  PasswordException, PasswordResponses, removeNullCharacters, setVerbosityLevel,
-  shadow, UnexpectedResponseException, UnknownErrorException,
-  UNSUPPORTED_FEATURES, Util, VERBOSITY_LEVELS
+  createBlob, createObjectURL, createPromiseCapability, InvalidPDFException,
+  isLittleEndian, MissingPDFException, OPS, PageViewport, PasswordException,
+  PasswordResponses, removeNullCharacters, shadow, UnexpectedResponseException,
+  UnknownErrorException, UNSUPPORTED_FEATURES, Util
 } from '../shared/util';
 import { DEFAULT_LINK_REL, getFilenameFromUrl, LinkTarget } from './dom_utils';
 import {
@@ -42,22 +41,6 @@ var PDFJS = globalScope.PDFJS;
 
 PDFJS.pdfBug = false;
 
-if (PDFJS.verbosity !== undefined) {
-  setVerbosityLevel(PDFJS.verbosity);
-}
-delete PDFJS.verbosity;
-Object.defineProperty(PDFJS, 'verbosity', {
-  get() {
-    return getVerbosityLevel();
-  },
-  set(level) {
-    setVerbosityLevel(level);
-  },
-  enumerable: true,
-  configurable: true,
-});
-
-PDFJS.VERBOSITY_LEVELS = VERBOSITY_LEVELS;
 PDFJS.OPS = OPS;
 PDFJS.UNSUPPORTED_FEATURES = UNSUPPORTED_FEATURES;
 PDFJS.shadow = shadow;
diff --git a/src/doc_helper.js b/src/doc_helper.js
index 86632b455..69b055144 100644
--- a/src/doc_helper.js
+++ b/src/doc_helper.js
@@ -23,20 +23,10 @@
  * to the PDF.js.
  * @constructor
  */
-function PDFJS() {
+function PDFJS() { // eslint-disable-line no-unused-vars
   // Mock class constructor. See src/display/api.js.
 }
 
-/**
- * Controls the logging level.
- * The constants from PDFJS.VERBOSITY_LEVELS should be used:
- * - errors
- * - warnings [default]
- * - infos
- * @var {number}
- */
-PDFJS.verbosity = PDFJS.VERBOSITY_LEVELS.warnings;
-
 /**
  * Represents the eventual result of an asynchronous operation.
  * @external Promise
diff --git a/src/pdf.js b/src/pdf.js
index a4b663af9..48657fb95 100644
--- a/src/pdf.js
+++ b/src/pdf.js
@@ -83,6 +83,7 @@ exports.NativeImageDecoding = pdfjsSharedUtil.NativeImageDecoding;
 exports.UnexpectedResponseException =
   pdfjsSharedUtil.UnexpectedResponseException;
 exports.OPS = pdfjsSharedUtil.OPS;
+exports.VerbosityLevel = pdfjsSharedUtil.VerbosityLevel;
 exports.UNSUPPORTED_FEATURES = pdfjsSharedUtil.UNSUPPORTED_FEATURES;
 exports.createValidAbsoluteUrl = pdfjsSharedUtil.createValidAbsoluteUrl;
 exports.createObjectURL = pdfjsSharedUtil.createObjectURL;
diff --git a/src/shared/util.js b/src/shared/util.js
index daac9f7bf..ec81372b5 100644
--- a/src/shared/util.js
+++ b/src/shared/util.js
@@ -142,10 +142,10 @@ var FontType = {
   MMTYPE1: 10,
 };
 
-var VERBOSITY_LEVELS = {
-  errors: 0,
-  warnings: 1,
-  infos: 5,
+const VerbosityLevel = {
+  ERRORS: 0,
+  WARNINGS: 1,
+  INFOS: 5,
 };
 
 var CMapCompressionType = {
@@ -251,10 +251,12 @@ var OPS = {
   constructPath: 91,
 };
 
-var verbosity = VERBOSITY_LEVELS.warnings;
+let verbosity = VerbosityLevel.WARNINGS;
 
 function setVerbosityLevel(level) {
-  verbosity = level;
+  if (Number.isInteger(level)) {
+    verbosity = level;
+  }
 }
 
 function getVerbosityLevel() {
@@ -265,19 +267,19 @@ function getVerbosityLevel() {
 // as warning that Workers were disabled, which is important to devs but not
 // end users.
 function info(msg) {
-  if (verbosity >= VERBOSITY_LEVELS.infos) {
+  if (verbosity >= VerbosityLevel.INFOS) {
     console.log('Info: ' + msg);
   }
 }
 
 // Non-fatal warnings.
 function warn(msg) {
-  if (verbosity >= VERBOSITY_LEVELS.warnings) {
+  if (verbosity >= VerbosityLevel.WARNINGS) {
     console.log('Warning: ' + msg);
   }
 }
 
-// Deprecated API function -- display regardless of the PDFJS.verbosity setting.
+// Deprecated API function -- display regardless of the `verbosity` setting.
 function deprecated(details) {
   console.log('Deprecated API usage: ' + details);
 }
@@ -1573,7 +1575,7 @@ export {
   FONT_IDENTITY_MATRIX,
   IDENTITY_MATRIX,
   OPS,
-  VERBOSITY_LEVELS,
+  VerbosityLevel,
   UNSUPPORTED_FEATURES,
   AnnotationBorderStyleType,
   AnnotationFieldFlag,
diff --git a/web/app.js b/web/app.js
index 7a7461081..f78bee346 100644
--- a/web/app.js
+++ b/web/app.js
@@ -740,6 +740,8 @@ let PDFViewerApplication = {
                PDFJSDev.test('FIREFOX || MOZCENTRAL || CHROME')) {
       parameters.docBaseUrl = this.baseUrl;
     }
+    // TODO: Remove this once all options are moved from the `PDFJS` object.
+    parameters.verbosity = PDFJS.verbosity;
 
     if (args) {
       for (let prop in args) {