diff --git a/gulpfile.mjs b/gulpfile.mjs
index 6d7033e40011e9..cd56bbf15b5eb1 100644
--- a/gulpfile.mjs
+++ b/gulpfile.mjs
@@ -863,11 +863,17 @@ async function parseDefaultPreferences(dir) {
     "./" + DEFAULT_PREFERENCES_DIR + dir + "app_options.mjs"
   );
 
-  const browserPrefs = AppOptions.getAll(OptionKind.BROWSER);
+  const browserPrefs = AppOptions.getAll(
+    OptionKind.BROWSER,
+    /* defaultOnly = */ true
+  );
   if (Object.keys(browserPrefs).length === 0) {
     throw new Error("No browser preferences found.");
   }
-  const prefs = AppOptions.getAll(OptionKind.PREFERENCE);
+  const prefs = AppOptions.getAll(
+    OptionKind.PREFERENCE,
+    /* defaultOnly = */ true
+  );
   if (Object.keys(prefs).length === 0) {
     throw new Error("No default preferences found.");
   }
diff --git a/test/unit/app_options_spec.js b/test/unit/app_options_spec.js
new file mode 100644
index 00000000000000..78981a7398eb2f
--- /dev/null
+++ b/test/unit/app_options_spec.js
@@ -0,0 +1,31 @@
+/* Copyright 2024 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 { AppOptions, OptionKind } from "../../web/app_options.js";
+import { objectSize } from "../../src/shared/util.js";
+
+describe("AppOptions", function () {
+  it("checks that getAll returns data, for every OptionKind", function () {
+    const KIND_NAMES = ["BROWSER", "VIEWER", "API", "WORKER", "PREFERENCE"];
+
+    for (const name of KIND_NAMES) {
+      const kind = OptionKind[name];
+      expect(typeof kind).toEqual("number");
+
+      const options = AppOptions.getAll(kind);
+      expect(objectSize(options)).toBeGreaterThan(0);
+    }
+  });
+});
diff --git a/test/unit/clitests.json b/test/unit/clitests.json
index 6ea14e1ed08b29..4a43e773f0d2b7 100644
--- a/test/unit/clitests.json
+++ b/test/unit/clitests.json
@@ -7,6 +7,7 @@
     "annotation_spec.js",
     "annotation_storage_spec.js",
     "api_spec.js",
+    "app_options_spec.js",
     "bidi_spec.js",
     "cff_parser_spec.js",
     "cmap_spec.js",
diff --git a/test/unit/jasmine-boot.js b/test/unit/jasmine-boot.js
index 5852ae6daa8f6c..da98ceeb313771 100644
--- a/test/unit/jasmine-boot.js
+++ b/test/unit/jasmine-boot.js
@@ -50,6 +50,7 @@ async function initializePDFJS(callback) {
       "pdfjs-test/unit/annotation_spec.js",
       "pdfjs-test/unit/annotation_storage_spec.js",
       "pdfjs-test/unit/api_spec.js",
+      "pdfjs-test/unit/app_options_spec.js",
       "pdfjs-test/unit/bidi_spec.js",
       "pdfjs-test/unit/cff_parser_spec.js",
       "pdfjs-test/unit/cmap_spec.js",
diff --git a/web/app_options.js b/web/app_options.js
index 998a6ed2c2bcb2..538d8ebf23ce39 100644
--- a/web/app_options.js
+++ b/web/app_options.js
@@ -404,6 +404,34 @@ if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
 
 const userOptions = Object.create(null);
 
+if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING || LIB")) {
+  // Ensure that the `defaultOptions` are correctly specified.
+  for (const name in defaultOptions) {
+    const { value, kind } = defaultOptions[name];
+
+    if (kind & OptionKind.PREFERENCE) {
+      if (kind & OptionKind.BROWSER) {
+        throw new Error(`Cannot mix "PREFERENCE" and "BROWSER" kind: ${name}`);
+      }
+      if (compatibilityParams[name] !== undefined) {
+        throw new Error(
+          `Should not have compatibility-value for "PREFERENCE" kind: ${name}`
+        );
+      }
+      const valueType = typeof value;
+
+      if (
+        valueType === "boolean" ||
+        valueType === "string" ||
+        (valueType === "number" && Number.isInteger(value))
+      ) {
+        continue; // Only "simple" values are allowed.
+      }
+      throw new Error(`Invalid value for "PREFERENCE" kind: ${name}`);
+    }
+  }
+}
+
 class AppOptions {
   constructor() {
     throw new Error("Cannot initialize AppOptions.");
@@ -421,36 +449,20 @@ class AppOptions {
     return undefined;
   }
 
-  static getAll(kind = null) {
+  static getAll(kind = null, defaultOnly = false) {
     const options = Object.create(null);
     for (const name in defaultOptions) {
       const defaultOption = defaultOptions[name];
-      if (kind) {
-        if (!(kind & defaultOption.kind)) {
-          continue;
-        }
-        if (
-          (typeof PDFJSDev === "undefined" || PDFJSDev.test("LIB")) &&
-          kind === OptionKind.PREFERENCE
-        ) {
-          if (defaultOption.kind & OptionKind.BROWSER) {
-            throw new Error(`Invalid kind for preference: ${name}`);
-          }
-          const value = defaultOption.value,
-            valueType = typeof value;
 
-          if (
-            valueType === "boolean" ||
-            valueType === "string" ||
-            (valueType === "number" && Number.isInteger(value))
-          ) {
-            options[name] = value;
-            continue;
-          }
-          throw new Error(`Invalid type for preference: ${name}`);
-        }
+      if (kind && !(kind & defaultOption.kind)) {
+        continue;
+      }
+      if (defaultOnly) {
+        options[name] = defaultOption.value;
+        continue;
       }
       const userOption = userOptions[name];
+
       options[name] =
         userOption !== undefined
           ? userOption
diff --git a/web/preferences.js b/web/preferences.js
index b669f37420ebc0..312176fa864f56 100644
--- a/web/preferences.js
+++ b/web/preferences.js
@@ -23,7 +23,7 @@ import { AppOptions, OptionKind } from "./app_options.js";
 class BasePreferences {
   #defaults = Object.freeze(
     typeof PDFJSDev === "undefined"
-      ? AppOptions.getAll(OptionKind.PREFERENCE)
+      ? AppOptions.getAll(OptionKind.PREFERENCE, /* defaultOnly = */ true)
       : PDFJSDev.eval("DEFAULT_PREFERENCES")
   );
 
@@ -48,7 +48,7 @@ class BasePreferences {
       ({ browserPrefs, prefs }) => {
         const BROWSER_PREFS =
           typeof PDFJSDev === "undefined"
-            ? AppOptions.getAll(OptionKind.BROWSER)
+            ? AppOptions.getAll(OptionKind.BROWSER, /* defaultOnly = */ true)
             : PDFJSDev.eval("BROWSER_PREFERENCES");
         const options = Object.create(null);