diff --git a/src/core/evaluator.js b/src/core/evaluator.js
index fe79687c5..a39bc2055 100644
--- a/src/core/evaluator.js
+++ b/src/core/evaluator.js
@@ -94,6 +94,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     nativeImageDecoderSupport: NativeImageDecoding.DECODE,
     ignoreErrors: false,
     isEvalSupported: true,
+    fontExtraProperties: false,
   };
 
   // eslint-disable-next-line no-shadow
@@ -807,6 +808,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                 loadedName: "g_font_error",
                 font: new ErrorFont(`Type3 font load error: ${reason}`),
                 dict: translated.font,
+                extraProperties: this.options.fontExtraProperties,
               });
             });
         })
@@ -956,15 +958,16 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     },
 
     loadFont: function PartialEvaluator_loadFont(fontName, font, resources) {
-      function errorFont() {
+      const errorFont = () => {
         return Promise.resolve(
           new TranslatedFont({
             loadedName: "g_font_error",
             font: new ErrorFont(`Font "${fontName}" is not available.`),
             dict: font,
+            extraProperties: this.options.fontExtraProperties,
           })
         );
-      }
+      };
 
       var fontRef,
         xref = this.xref;
@@ -1096,7 +1099,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
       }
 
       translatedPromise
-        .then(function(translatedFont) {
+        .then(translatedFont => {
           if (translatedFont.fontType !== undefined) {
             var xrefFontStats = xref.stats.fontTypes;
             xrefFontStats[translatedFont.fontType] = true;
@@ -1107,6 +1110,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
               loadedName: font.loadedName,
               font: translatedFont,
               dict: font,
+              extraProperties: this.options.fontExtraProperties,
             })
           );
         })
@@ -1136,6 +1140,7 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
                 reason instanceof Error ? reason.message : reason
               ),
               dict: font,
+              extraProperties: this.options.fontExtraProperties,
             })
           );
         });
@@ -3273,10 +3278,11 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
 })();
 
 class TranslatedFont {
-  constructor({ loadedName, font, dict }) {
+  constructor({ loadedName, font, dict, extraProperties = false }) {
     this.loadedName = loadedName;
     this.font = font;
     this.dict = dict;
+    this._extraProperties = extraProperties;
     this.type3Loaded = null;
     this.sent = false;
   }
@@ -3290,7 +3296,7 @@ class TranslatedFont {
     handler.send("commonobj", [
       this.loadedName,
       "Font",
-      this.font.exportData(),
+      this.font.exportData(this._extraProperties),
     ]);
   }
 
diff --git a/src/core/fonts.js b/src/core/fonts.js
index add8fd973..241e50daf 100644
--- a/src/core/fonts.js
+++ b/src/core/fonts.js
@@ -92,21 +92,17 @@ const EXPORT_DATA_PROPERTIES = [
   "bbox",
   "black",
   "bold",
-  "cMap",
   "charProcOperatorList",
   "composite",
   "data",
-  "defaultEncoding",
   "defaultVMetrics",
   "defaultWidth",
   "descent",
-  "differences",
   "fallbackName",
   "fontMatrix",
   "fontType",
   "isMonospace",
   "isSerifFont",
-  "isSymbolicFont",
   "isType3Font",
   "italic",
   "loadedName",
@@ -114,12 +110,19 @@ const EXPORT_DATA_PROPERTIES = [
   "missingFile",
   "name",
   "remeasure",
-  "seacMap",
   "subtype",
-  "toFontChar",
-  "toUnicode",
   "type",
   "vertical",
+];
+
+const EXPORT_DATA_EXTRA_PROPERTIES = [
+  "cMap",
+  "defaultEncoding",
+  "differences",
+  "isSymbolicFont",
+  "seacMap",
+  "toFontChar",
+  "toUnicode",
   "vmetrics",
   "widths",
 ];
@@ -1295,10 +1298,14 @@ var Font = (function FontClosure() {
       return shadow(this, "renderer", renderer);
     },
 
-    exportData() {
+    exportData(extraProperties = false) {
+      const exportDataProperties = extraProperties
+        ? [...EXPORT_DATA_PROPERTIES, ...EXPORT_DATA_EXTRA_PROPERTIES]
+        : EXPORT_DATA_PROPERTIES;
+
       const data = Object.create(null);
       let property, value;
-      for (property of EXPORT_DATA_PROPERTIES) {
+      for (property of exportDataProperties) {
         value = this[property];
         // Ignore properties that haven't been explicitly set.
         if (value !== undefined) {
@@ -3352,7 +3359,7 @@ var ErrorFont = (function ErrorFontClosure() {
     charsToGlyphs: function ErrorFont_charsToGlyphs() {
       return [];
     },
-    exportData: function ErrorFont_exportData() {
+    exportData(extraProperties = false) {
       return { error: this.error };
     },
   };
diff --git a/src/core/worker.js b/src/core/worker.js
index ba565a487..b9afe7bed 100644
--- a/src/core/worker.js
+++ b/src/core/worker.js
@@ -403,6 +403,7 @@ var WorkerMessageHandler = {
         nativeImageDecoderSupport: data.nativeImageDecoderSupport,
         ignoreErrors: data.ignoreErrors,
         isEvalSupported: data.isEvalSupported,
+        fontExtraProperties: data.fontExtraProperties,
       };
 
       getPdfManager(data, evaluatorOptions)
diff --git a/src/display/api.js b/src/display/api.js
index 4f5749f35..8921cc690 100644
--- a/src/display/api.js
+++ b/src/display/api.js
@@ -145,6 +145,11 @@ function setPDFNetworkStreamFactory(pdfNetworkStreamFactory) {
  *   converted to OpenType fonts and loaded via font face rules. If disabled,
  *   fonts will be rendered using a built-in font renderer that constructs the
  *   glyphs with primitive path commands. The default value is `false`.
+ * @property {boolean} [fontExtraProperties] - Include additional properties,
+ *   which are unused during rendering of PDF documents, when exporting the
+ *   parsed font data from the worker-thread. This may be useful for debugging
+ *   purposes (and backwards compatibility), but note that it will lead to
+ *   increased memory usage. The default value is `false`.
  * @property {boolean} [disableRange] - Disable range request loading
  *   of PDF files. When enabled, and if the server supports partial content
  *   requests, then the PDF will be fetched in chunks.
@@ -251,6 +256,7 @@ function getDocument(src) {
   params.rangeChunkSize = params.rangeChunkSize || DEFAULT_RANGE_CHUNK_SIZE;
   params.CMapReaderFactory = params.CMapReaderFactory || DOMCMapReaderFactory;
   params.ignoreErrors = params.stopAtErrors !== true;
+  params.fontExtraProperties = params.fontExtraProperties === true;
   params.pdfBug = params.pdfBug === true;
 
   const NativeImageDecoderValues = Object.values(NativeImageDecoding);
@@ -403,6 +409,7 @@ function _fetchDocument(worker, source, pdfDataRangeTransport, docId) {
       nativeImageDecoderSupport: source.nativeImageDecoderSupport,
       ignoreErrors: source.ignoreErrors,
       isEvalSupported: source.isEvalSupported,
+      fontExtraProperties: source.fontExtraProperties,
     })
     .then(function(workerId) {
       if (worker.destroyed) {
diff --git a/web/app.js b/web/app.js
index 5ddfd8adf..135882176 100644
--- a/web/app.js
+++ b/web/app.js
@@ -309,6 +309,8 @@ const PDFViewerApplication = {
     }
     if ("pdfbug" in hashParams) {
       AppOptions.set("pdfBug", true);
+      AppOptions.set("fontExtraProperties", true);
+
       const enabled = hashParams["pdfbug"].split(",");
       waitOn.push(loadAndEnablePDFBug(enabled));
     }
diff --git a/web/app_options.js b/web/app_options.js
index 3fa1187a1..0f3b5af25 100644
--- a/web/app_options.js
+++ b/web/app_options.js
@@ -193,6 +193,11 @@ const defaultOptions = {
     value: "",
     kind: OptionKind.API,
   },
+  fontExtraProperties: {
+    /** @type {boolean} */
+    value: false,
+    kind: OptionKind.API,
+  },
   isEvalSupported: {
     /** @type {boolean} */
     value: true,