diff --git a/src/client/shared/postmessage.ts b/src/client/shared/postmessage.ts
index c9b0310..33b1054 100644
--- a/src/client/shared/postmessage.ts
+++ b/src/client/shared/postmessage.ts
@@ -63,10 +63,9 @@ export default function (client: ScramjetClient) {
 			},
 		});
 
-	const toproxy = [
-		"Worker.prototype.postMessage",
-		"MessagePort.prototype.postMessage",
-	];
+	const toproxy = ["MessagePort.prototype.postMessage"];
+
+	if (self.Worker) toproxy.push("Worker.prototype.postMessage");
 	if (!iswindow) toproxy.push("self.postMessage"); // only do the generic version if we're in a worker
 
 	client.Proxy(toproxy, {
diff --git a/src/client/shared/requests/xmlhttprequest.ts b/src/client/shared/requests/xmlhttprequest.ts
index 05ea88e..6af7e71 100644
--- a/src/client/shared/requests/xmlhttprequest.ts
+++ b/src/client/shared/requests/xmlhttprequest.ts
@@ -1,9 +1,18 @@
-import { config, decodeUrl, encodeUrl, rewriteHeaders } from "../../../shared";
+import { config, decodeUrl, encodeUrl } from "../../../shared";
 import { ScramjetClient } from "../../client";
-const nativeworker = Worker;
-const postmessage = Worker.prototype.postMessage;
+let nativeworker;
+let postmessage;
+
+if (self.Worker) {
+	nativeworker = Worker;
+	postmessage = Worker.prototype.postMessage;
+}
+
 export default function (client: ScramjetClient, self: Self) {
-	const worker = new nativeworker(config.sync);
+	let worker;
+	if (self.Worker) {
+		worker = new nativeworker(config.sync);
+	}
 	const ARGS = Symbol("xhr original args");
 	const HEADERS = Symbol("xhr headers");
 
diff --git a/src/client/shared/worker.ts b/src/client/shared/worker.ts
index f042fe1..f348b5f 100644
--- a/src/client/shared/worker.ts
+++ b/src/client/shared/worker.ts
@@ -4,8 +4,11 @@ import { encodeUrl } from "../../shared/rewriters/url";
 import type { MessageC2W } from "../../worker";
 import { ScramjetClient } from "../client";
 
-const workerpostmessage = Worker.prototype.postMessage;
-
+const sharedworkerpostmessage = MessagePort.prototype.postMessage;
+let workerpostmessage;
+if (self.Worker) {
+	workerpostmessage = Worker.prototype.postMessage;
+}
 export default function (client: ScramjetClient, self: typeof globalThis) {
 	const handler = {
 		construct({ args, call }) {
@@ -39,14 +42,26 @@ export default function (client: ScramjetClient, self: typeof globalThis) {
 
 			(async () => {
 				const port = await conn.getInnerPort();
-				workerpostmessage.call(
-					worker,
-					{
-						$scramjet$type: "baremuxinit",
-						port,
-					},
-					[port]
-				);
+				if (worker instanceof Worker) {
+					workerpostmessage.call(
+						worker,
+						{
+							$scramjet$type: "baremuxinit",
+							port,
+						},
+						[port]
+					);
+				}
+				if (worker instanceof SharedWorker) {
+					sharedworkerpostmessage.call(
+						worker.port,
+						{
+							$scramjet$type: "baremuxinit",
+							port,
+						},
+						[port]
+					);
+				}
 			})();
 		},
 	};