diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index 1b1dc1b73..243c225ba 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -96,8 +96,9 @@ const DefaultPartialEvaluatorOptions = Object.freeze({
   ignoreErrors: false,
   isEvalSupported: true,
   fontExtraProperties: false,
-  standardFontDataUrl: null,
   useSystemFonts: true,
+  cMapUrl: null,
+  standardFontDataUrl: null,
 });
 
 const PatternType = {
@@ -360,23 +361,25 @@ class PartialEvaluator {
     if (cachedData) {
       return cachedData;
     }
-    const readableStream = this.handler.sendWithStream("FetchBuiltInCMap", {
-      name,
-    });
-    const reader = readableStream.getReader();
+    let data;
 
-    const data = await new Promise(function (resolve, reject) {
-      function pump() {
-        reader.read().then(function ({ value, done }) {
-          if (done) {
-            return;
-          }
-          resolve(value);
-          pump();
-        }, reject);
+    if (this.options.cMapUrl !== null) {
+      // Only compressed CMaps are (currently) supported here.
+      const url = `${this.options.cMapUrl}${name}.bcmap`;
+      const response = await fetch(url);
+      if (!response.ok) {
+        throw new Error(
+          `fetchBuiltInCMap: failed to fetch file "${url}" with "${response.statusText}".`
+        );
       }
-      pump();
-    });
+      data = {
+        cMapData: new Uint8Array(await response.arrayBuffer()),
+        compressionType: CMapCompressionType.BINARY,
+      };
+    } else {
+      // Get the data on the main-thread instead.
+      data = await this.handler.sendWithPromise("FetchBuiltInCMap", { name });
+    }
 
     if (data.compressionType !== CMapCompressionType.NONE) {
       // Given the size of uncompressed CMaps, only cache compressed ones.
diff --git a/src/core/worker.js b/src/core/worker.js
index a69b76743..2ce3ef206 100644
--- a/src/core/worker.js
+++ b/src/core/worker.js
@@ -412,6 +412,7 @@ class WorkerMessageHandler {
         isEvalSupported: data.isEvalSupported,
         fontExtraProperties: data.fontExtraProperties,
         useSystemFonts: data.useSystemFonts,
+        cMapUrl: data.cMapUrl,
         standardFontDataUrl: data.standardFontDataUrl,
       };
 
diff --git a/src/display/api.js b/src/display/api.js
index c319802ad..056e343cc 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -152,19 +152,19 @@ function setPDFNetworkStreamFactory(pdfNetworkStreamFactory) {
  *   reading built-in CMap files. Providing a custom factory is useful for
  *   environments without Fetch API or `XMLHttpRequest` support, such as
  *   Node.js. The default value is {DOMCMapReaderFactory}.
- * @property {boolean} [useSystemFonts] - When true, fonts that aren't embedded
- *   in the PDF will fallback to a system font. Defaults to true for web
- *   environments and false for node.
+ * @property {boolean} [useSystemFonts] - When `true`, fonts that aren't
+ *   embedded in the PDF document will fallback to a system font.
+ *   The default value is `true` in web environments and `false` in Node.js.
  * @property {string} [standardFontDataUrl] - The URL where the standard font
  *   files are located. Include the trailing slash.
- * @property {boolean} [useWorkerFetch] - Enable using fetch in the worker for
- *   resources. This currently only used for fetching the font data from the
- *   worker thread. When `true`, StandardFontDataFactory will be ignored. The
- *   default value is `true` in web environment and `false` for Node.
  * @property {Object} [StandardFontDataFactory] - The factory that will be used
  *   when reading the standard font files. Providing a custom factory is useful
  *   for environments without Fetch API or `XMLHttpRequest` support, such as
  *   Node.js. The default value is {DOMStandardFontDataFactory}.
+ * @property {boolean} [useWorkerFetch] - Enable using the Fetch API in the
+ *   worker-thread when reading CMap and standard font files. When `true`,
+ *   the `CMapReaderFactory` and `StandardFontDataFactory` options are ignored.
+ *   The default value is `true` in web wenvironments and `false` in Node.js.
  * @property {boolean} [stopAtErrors] - Reject certain promises, e.g.
  *   `getOperatorList`, `getTextContent`, and `RenderTask`, when the associated
  *   PDF data cannot be successfully parsed, instead of attempting to recover
@@ -333,6 +333,7 @@ function getDocument(src) {
   }
   if (typeof params.useWorkerFetch !== "boolean") {
     params.useWorkerFetch =
+      params.CMapReaderFactory === DOMCMapReaderFactory &&
       params.StandardFontDataFactory === DOMStandardFontDataFactory;
   }
   if (typeof params.isEvalSupported !== "boolean") {
@@ -487,6 +488,7 @@ function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
       fontExtraProperties: source.fontExtraProperties,
       enableXfa: source.enableXfa,
       useSystemFonts: source.useSystemFonts,
+      cMapUrl: source.useWorkerFetch ? source.cMapUrl : null,
       standardFontDataUrl: source.useWorkerFetch
         ? source.standardFontDataUrl
         : null,
@@ -2680,36 +2682,19 @@ class WorkerTransport {
       this._onUnsupportedFeature.bind(this)
     );
 
+    messageHandler.on("FetchBuiltInCMap", data => {
+      if (this.destroyed) {
+        return Promise.reject(new Error("Worker was destroyed"));
+      }
+      return this.CMapReaderFactory.fetch(data);
+    });
+
     messageHandler.on("FetchStandardFontData", data => {
       if (this.destroyed) {
         return Promise.reject(new Error("Worker was destroyed"));
       }
       return this.StandardFontDataFactory.fetch(data);
     });
-
-    messageHandler.on("FetchBuiltInCMap", (data, sink) => {
-      if (this.destroyed) {
-        sink.error(new Error("Worker was destroyed"));
-        return;
-      }
-      let fetched = false;
-
-      sink.onPull = () => {
-        if (fetched) {
-          sink.close();
-          return;
-        }
-        fetched = true;
-
-        this.CMapReaderFactory.fetch(data)
-          .then(function (builtInCMap) {
-            sink.enqueue(builtInCMap, 1, [builtInCMap.cMapData.buffer]);
-          })
-          .catch(function (reason) {
-            sink.error(reason);
-          });
-      };
-    });
   }
 
   _onUnsupportedFeature({ featureId }) {
diff --git a/src/display/base_factory.js b/src/display/base_factory.js
new file mode 100644
index 000000000..fa880c155
--- /dev/null
+++ b/src/display/base_factory.js
@@ -0,0 +1,129 @@
+/* Copyright 2015 Mozilla Foundation
+ *
+ * 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.
+ */
+
+import { CMapCompressionType, unreachable } from "../shared/util.js";
+
+class BaseCanvasFactory {
+  constructor() {
+    if (this.constructor === BaseCanvasFactory) {
+      unreachable("Cannot initialize BaseCanvasFactory.");
+    }
+  }
+
+  create(width, height) {
+    unreachable("Abstract method `create` called.");
+  }
+
+  reset(canvasAndContext, width, height) {
+    if (!canvasAndContext.canvas) {
+      throw new Error("Canvas is not specified");
+    }
+    if (width <= 0 || height <= 0) {
+      throw new Error("Invalid canvas size");
+    }
+    canvasAndContext.canvas.width = width;
+    canvasAndContext.canvas.height = height;
+  }
+
+  destroy(canvasAndContext) {
+    if (!canvasAndContext.canvas) {
+      throw new Error("Canvas is not specified");
+    }
+    // Zeroing the width and height cause Firefox to release graphics
+    // resources immediately, which can greatly reduce memory consumption.
+    canvasAndContext.canvas.width = 0;
+    canvasAndContext.canvas.height = 0;
+    canvasAndContext.canvas = null;
+    canvasAndContext.context = null;
+  }
+}
+
+class BaseCMapReaderFactory {
+  constructor({ baseUrl = null, isCompressed = false }) {
+    if (this.constructor === BaseCMapReaderFactory) {
+      unreachable("Cannot initialize BaseCMapReaderFactory.");
+    }
+    this.baseUrl = baseUrl;
+    this.isCompressed = isCompressed;
+  }
+
+  async fetch({ name }) {
+    if (!this.baseUrl) {
+      throw new Error(
+        'The CMap "baseUrl" parameter must be specified, ensure that ' +
+          'the "cMapUrl" and "cMapPacked" API parameters are provided.'
+      );
+    }
+    if (!name) {
+      throw new Error("CMap name must be specified.");
+    }
+    const url = this.baseUrl + name + (this.isCompressed ? ".bcmap" : "");
+    const compressionType = this.isCompressed
+      ? CMapCompressionType.BINARY
+      : CMapCompressionType.NONE;
+
+    return this._fetchData(url, compressionType).catch(reason => {
+      throw new Error(
+        `Unable to load ${this.isCompressed ? "binary " : ""}CMap at: ${url}`
+      );
+    });
+  }
+
+  /**
+   * @private
+   */
+  _fetchData(url, compressionType) {
+    unreachable("Abstract method `_fetchData` called.");
+  }
+}
+
+class BaseStandardFontDataFactory {
+  constructor({ baseUrl = null }) {
+    if (this.constructor === BaseStandardFontDataFactory) {
+      unreachable("Cannot initialize BaseStandardFontDataFactory.");
+    }
+    this.baseUrl = baseUrl;
+  }
+
+  async fetch({ filename }) {
+    if (!this.baseUrl) {
+      throw new Error(
+        'The standard font "baseUrl" parameter must be specified, ensure that ' +
+          'the "standardFontDataUrl" API parameter is provided.'
+      );
+    }
+    if (!filename) {
+      throw new Error("Font filename must be specified.");
+    }
+    const url = this.baseUrl + filename + ".pfb";
+
+    return this._fetchData(url).catch(reason => {
+      throw new Error(`Unable to load font data at: ${url}`);
+    });
+  }
+
+  /**
+   * @private
+   */
+  _fetchData(url) {
+    unreachable("Abstract method `_fetchData` called.");
+  }
+}
+
+export {
+  BaseCanvasFactory,
+  BaseCMapReaderFactory,
+  BaseStandardFontDataFactory,
+};
diff --git a/src/display/display_utils.js b/src/display/display_utils.js
index 06b6f6e67..72f25810e 100644
--- a/src/display/display_utils.js
+++ b/src/display/display_utils.js
@@ -16,53 +16,21 @@
 import {
   assert,
   BaseException,
-  CMapCompressionType,
   isString,
   removeNullCharacters,
   stringToBytes,
-  unreachable,
   Util,
   warn,
 } from "../shared/util.js";
+import {
+  BaseCanvasFactory,
+  BaseCMapReaderFactory,
+  BaseStandardFontDataFactory,
+} from "./base_factory.js";
 
 const DEFAULT_LINK_REL = "noopener noreferrer nofollow";
 const SVG_NS = "http://www.w3.org/2000/svg";
 
-class BaseCanvasFactory {
-  constructor() {
-    if (this.constructor === BaseCanvasFactory) {
-      unreachable("Cannot initialize BaseCanvasFactory.");
-    }
-  }
-
-  create(width, height) {
-    unreachable("Abstract method `create` called.");
-  }
-
-  reset(canvasAndContext, width, height) {
-    if (!canvasAndContext.canvas) {
-      throw new Error("Canvas is not specified");
-    }
-    if (width <= 0 || height <= 0) {
-      throw new Error("Invalid canvas size");
-    }
-    canvasAndContext.canvas.width = width;
-    canvasAndContext.canvas.height = height;
-  }
-
-  destroy(canvasAndContext) {
-    if (!canvasAndContext.canvas) {
-      throw new Error("Canvas is not specified");
-    }
-    // Zeroing the width and height cause Firefox to release graphics
-    // resources immediately, which can greatly reduce memory consumption.
-    canvasAndContext.canvas.width = 0;
-    canvasAndContext.canvas.height = 0;
-    canvasAndContext.canvas = null;
-    canvasAndContext.context = null;
-  }
-}
-
 class DOMCanvasFactory extends BaseCanvasFactory {
   constructor({ ownerDocument = globalThis.document } = {}) {
     super();
@@ -134,45 +102,6 @@ function fetchData(url, asTypedArray) {
   });
 }
 
-class BaseCMapReaderFactory {
-  constructor({ baseUrl = null, isCompressed = false }) {
-    if (this.constructor === BaseCMapReaderFactory) {
-      unreachable("Cannot initialize BaseCMapReaderFactory.");
-    }
-    this.baseUrl = baseUrl;
-    this.isCompressed = isCompressed;
-  }
-
-  async fetch({ name }) {
-    if (!this.baseUrl) {
-      throw new Error(
-        'The CMap "baseUrl" parameter must be specified, ensure that ' +
-          'the "cMapUrl" and "cMapPacked" API parameters are provided.'
-      );
-    }
-    if (!name) {
-      throw new Error("CMap name must be specified.");
-    }
-    const url = this.baseUrl + name + (this.isCompressed ? ".bcmap" : "");
-    const compressionType = this.isCompressed
-      ? CMapCompressionType.BINARY
-      : CMapCompressionType.NONE;
-
-    return this._fetchData(url, compressionType).catch(reason => {
-      throw new Error(
-        `Unable to load ${this.isCompressed ? "binary " : ""}CMap at: ${url}`
-      );
-    });
-  }
-
-  /**
-   * @private
-   */
-  _fetchData(url, compressionType) {
-    unreachable("Abstract method `_fetchData` called.");
-  }
-}
-
 class DOMCMapReaderFactory extends BaseCMapReaderFactory {
   _fetchData(url, compressionType) {
     return fetchData(url, /* asTypedArray = */ this.isCompressed).then(data => {
@@ -181,32 +110,6 @@ class DOMCMapReaderFactory extends BaseCMapReaderFactory {
   }
 }
 
-class BaseStandardFontDataFactory {
-  constructor({ baseUrl = null }) {
-    if (this.constructor === BaseStandardFontDataFactory) {
-      unreachable("Cannot initialize BaseStandardFontDataFactory.");
-    }
-    this.baseUrl = baseUrl;
-  }
-
-  async fetch({ filename }) {
-    if (!this.baseUrl) {
-      throw new Error(
-        'The standard font "baseUrl" parameter must be specified, ensure that ' +
-          'the "standardFontDataUrl" API parameter is provided.'
-      );
-    }
-    if (!filename) {
-      throw new Error("Font filename must be specified.");
-    }
-    const url = this.baseUrl + filename + ".pfb";
-
-    return this._fetchData(url).catch(reason => {
-      throw new Error(`Unable to load font data at: ${url}`);
-    });
-  }
-}
-
 class DOMStandardFontDataFactory extends BaseStandardFontDataFactory {
   _fetchData(url) {
     return fetchData(url, /* asTypedArray = */ true);
@@ -740,9 +643,6 @@ class PDFDateString {
 
 export {
   addLinkAttributes,
-  BaseCanvasFactory,
-  BaseCMapReaderFactory,
-  BaseStandardFontDataFactory,
   DEFAULT_LINK_REL,
   deprecated,
   DOMCanvasFactory,
diff --git a/src/display/node_utils.js b/src/display/node_utils.js
index f40155b83..cf8a387c5 100644
--- a/src/display/node_utils.js
+++ b/src/display/node_utils.js
@@ -18,23 +18,10 @@ import {
   BaseCanvasFactory,
   BaseCMapReaderFactory,
   BaseStandardFontDataFactory,
-} from "./display_utils.js";
+} from "./base_factory.js";
 import { isNodeJS } from "../shared/is_node.js";
 import { unreachable } from "../shared/util.js";
 
-function fetchData(url) {
-  return new Promise((resolve, reject) => {
-    const fs = __non_webpack_require__("fs");
-    fs.readFile(url, (error, data) => {
-      if (error || !data) {
-        reject(new Error(error));
-        return;
-      }
-      resolve(new Uint8Array(data));
-    });
-  });
-}
-
 let NodeCanvasFactory = class {
   constructor() {
     unreachable("Not implemented: NodeCanvasFactory");
@@ -54,6 +41,19 @@ let NodeStandardFontDataFactory = class {
 };
 
 if ((typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) && isNodeJS) {
+  const fetchData = function (url) {
+    return new Promise((resolve, reject) => {
+      const fs = __non_webpack_require__("fs");
+      fs.readFile(url, (error, data) => {
+        if (error || !data) {
+          reject(new Error(error));
+          return;
+        }
+        resolve(new Uint8Array(data));
+      });
+    });
+  };
+
   NodeCanvasFactory = class extends BaseCanvasFactory {
     create(width, height) {
       if (width <= 0 || height <= 0) {
diff --git a/test/driver.js b/test/driver.js
index 70eacaab9..f4c7bde42 100644
--- a/test/driver.js
+++ b/test/driver.js
@@ -19,7 +19,7 @@
 
 const WAITING_TIME = 100; // ms
 const PDF_TO_CSS_UNITS = 96.0 / 72.0;
-const CMAP_URL = "../external/bcmaps/";
+const CMAP_URL = "/build/generic/web/cmaps/";
 const CMAP_PACKED = true;
 const STANDARD_FONT_DATA_URL = "/build/generic/web/standard_fonts/";
 const IMAGE_RESOURCES_PATH = "/web/images/";
diff --git a/test/test_manifest.json b/test/test_manifest.json
index b84fbd7ac..4eb7c0cbf 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -4046,6 +4046,15 @@
       "lastPage": 1,
       "type": "eq"
     },
+    {  "id": "mao-main_thread_fetch",
+       "file": "pdfs/mao.pdf",
+       "md5": "797093d67c4d4d4231ac6e1fb66bf6c3",
+       "rounds": 1,
+       "link": true,
+       "lastPage": 1,
+       "type": "eq",
+       "useWorkerFetch": false
+    },
     {  "id": "mao-text",
        "file": "pdfs/mao.pdf",
        "md5": "797093d67c4d4d4231ac6e1fb66bf6c3",