diff --git a/src/core/catalog.js b/src/core/catalog.js
index 8611eab9b5e570..15d225bc92a6dd 100644
--- a/src/core/catalog.js
+++ b/src/core/catalog.js
@@ -25,7 +25,6 @@ import {
   DocumentActionEventType,
   FormatError,
   info,
-  isBool,
   isString,
   objectSize,
   PermissionFlag,
@@ -221,7 +220,7 @@ class Catalog {
         continue;
       }
       const value = obj.get(key);
-      if (!isBool(value)) {
+      if (typeof value !== "boolean") {
         continue;
       }
       markInfo[key] = value;
@@ -1521,7 +1520,7 @@ class Catalog {
           }
           // The 'NewWindow' property, equal to `LinkTarget.BLANK`.
           const newWindow = action.get("NewWindow");
-          if (isBool(newWindow)) {
+          if (typeof newWindow === "boolean") {
             resultObj.newWindow = newWindow;
           }
           break;
diff --git a/src/core/function.js b/src/core/function.js
index d402d067bd534e..37710610f8be40 100644
--- a/src/core/function.js
+++ b/src/core/function.js
@@ -17,7 +17,6 @@ import { Dict, Ref } from "./primitives.js";
 import {
   FormatError,
   info,
-  isBool,
   IsEvalSupportedCached,
   shadow,
   unreachable,
@@ -627,7 +626,7 @@ class PostScriptEvaluator {
         case "and":
           b = stack.pop();
           a = stack.pop();
-          if (isBool(a) && isBool(b)) {
+          if (typeof a === "boolean" && typeof b === "boolean") {
             stack.push(a && b);
           } else {
             stack.push(a & b);
@@ -751,7 +750,7 @@ class PostScriptEvaluator {
           break;
         case "not":
           a = stack.pop();
-          if (isBool(a)) {
+          if (typeof a === "boolean") {
             stack.push(!a);
           } else {
             stack.push(~a);
@@ -760,7 +759,7 @@ class PostScriptEvaluator {
         case "or":
           b = stack.pop();
           a = stack.pop();
-          if (isBool(a) && isBool(b)) {
+          if (typeof a === "boolean" && typeof b === "boolean") {
             stack.push(a || b);
           } else {
             stack.push(a | b);
@@ -802,7 +801,7 @@ class PostScriptEvaluator {
         case "xor":
           b = stack.pop();
           a = stack.pop();
-          if (isBool(a) && isBool(b)) {
+          if (typeof a === "boolean" && typeof b === "boolean") {
             stack.push(a !== b);
           } else {
             stack.push(a ^ b);
diff --git a/src/shared/util.js b/src/shared/util.js
index 4e84ea58dc4270..de0a2e5c5bb9a9 100644
--- a/src/shared/util.js
+++ b/src/shared/util.js
@@ -1030,10 +1030,6 @@ function utf8StringToString(str) {
   return unescape(encodeURIComponent(str));
 }
 
-function isBool(v) {
-  return typeof v === "boolean";
-}
-
 function isString(v) {
   return typeof v === "string";
 }
@@ -1139,7 +1135,6 @@ export {
   isArrayBuffer,
   isArrayEqual,
   isAscii,
-  isBool,
   IsEvalSupportedCached,
   IsLittleEndianCached,
   isSameOrigin,
diff --git a/test/unit/util_spec.js b/test/unit/util_spec.js
index 8f70e7054f8b04..506cc8480858f1 100644
--- a/test/unit/util_spec.js
+++ b/test/unit/util_spec.js
@@ -21,7 +21,6 @@ import {
   getModificationDate,
   isArrayBuffer,
   isAscii,
-  isBool,
   isSameOrigin,
   isString,
   string32,
@@ -74,22 +73,6 @@ describe("util", function () {
     });
   });
 
-  describe("isBool", function () {
-    it("handles boolean values", function () {
-      expect(isBool(true)).toEqual(true);
-      expect(isBool(false)).toEqual(true);
-    });
-
-    it("handles non-boolean values", function () {
-      expect(isBool("true")).toEqual(false);
-      expect(isBool("false")).toEqual(false);
-      expect(isBool(1)).toEqual(false);
-      expect(isBool(0)).toEqual(false);
-      expect(isBool(null)).toEqual(false);
-      expect(isBool(undefined)).toEqual(false);
-    });
-  });
-
   describe("isString", function () {
     it("handles string values", function () {
       expect(isString("foo")).toEqual(true);