diff --git a/README.md b/README.md
index 8279770..cf5c90c 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,10 @@ if (isJsDom) {
 if (isDeno) {
   // do deno only stuff
 }
+
+if (isHappyDom) {
+  // do happy-dom only stuff
+}
 ```
 
 ES5 style import
@@ -64,8 +68,12 @@ if (jsEnv.isJsDom) {
 if (jsEnv.isDeno) {
   // do deno only stuff
 }
+
+if (jsEnv.isHappyDom) {
+  // do happy DOM only stuff
+}
 ```
 
 ## License
 
-MIT © Dineshkumar Pandiyan
\ No newline at end of file
+MIT © Dineshkumar Pandiyan
diff --git a/src/index.d.ts b/src/index.d.ts
index a461086..623a0e3 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -3,3 +3,4 @@ export declare const isWebWorker: boolean;
 export declare const isNode: boolean;
 export declare const isJsDom: boolean;
 export declare const isDeno: boolean;
+export declare const isHappyDom: boolean;
diff --git a/src/index.js b/src/index.js
index 787dcda..cb2beff 100644
--- a/src/index.js
+++ b/src/index.js
@@ -21,9 +21,15 @@ const isJsDom =
     (navigator.userAgent.includes("Node.js") ||
       navigator.userAgent.includes("jsdom")));
 
+/**
+ * @see https://github.com/capricorn86/happy-dom/discussions/481
+ */
+const isHappyDom =
+  typeof window !== "undefined" && typeof navigator !== "undefined" && typeof window.happyDOM !== "undefined";
+
 const isDeno =
   typeof Deno !== "undefined" &&
   typeof Deno.version !== "undefined" &&
   typeof Deno.version.deno !== "undefined";
 
-export { isBrowser, isWebWorker, isNode, isJsDom, isDeno };
+export { isBrowser, isWebWorker, isNode, isJsDom, isDeno, isHappyDom };
diff --git a/test/index.js b/test/index.js
index 14cd4d9..77689ef 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,5 +1,5 @@
 import { assert } from "chai";
-import { isBrowser, isNode, isWebWorker, isDeno, isJsDom } from "../src";
+import { isBrowser, isNode, isWebWorker, isDeno, isJsDom, isHappyDom } from "../src";
 
 console.log({
   isBrowser,
@@ -7,6 +7,7 @@ console.log({
   isWebWorker,
   isJsDom,
   isDeno,
+  isHappyDom,
 });
 
 describe("Browser or Node.js", () => {