diff --git a/src/client/client.ts b/src/client/client.ts
index 1e16865..484371c 100644
--- a/src/client/client.ts
+++ b/src/client/client.ts
@@ -98,9 +98,13 @@ export class ScramjetClient {
 		} else {
 			this.bare = new BareClient(
 				new Promise((resolve) => {
-					addEventListener("message", (e) => {
-						if (e.data instanceof MessagePort) {
-							resolve(e.data);
+					addEventListener("message", ({ data }) => {
+						if (typeof data !== "object") return;
+						if (
+							"$scramjet$type" in data &&
+							data.$scramjet$type === "baremuxinit"
+						) {
+							resolve(data.port);
 						}
 					});
 				})
diff --git a/src/client/dom/postmessage.ts b/src/client/dom/postmessage.ts
index 840f186..c39edc4 100644
--- a/src/client/dom/postmessage.ts
+++ b/src/client/dom/postmessage.ts
@@ -1,3 +1,4 @@
+import { iswindow } from "..";
 import { SCRAMJETCLIENT } from "../../symbols";
 import { ScramjetClient } from "../client";
 import { POLLUTANT } from "../shared/realm";
@@ -32,6 +33,7 @@ export default function (client: ScramjetClient) {
 			);
 
 			ctx.args[0] = {
+				$scramjet$messagetype: "window",
 				$scramjet$origin: callerClient.url.origin,
 				$scramjet$data: ctx.args[0],
 			};
@@ -44,4 +46,21 @@ export default function (client: ScramjetClient) {
 			);
 		},
 	});
+
+	const toproxy = [
+		"Worker.prototype.postMessage",
+		"MessagePort.prototype.postMessage",
+	];
+	if (!iswindow) toproxy.push("self.postMessage"); // only do the generic version if we're in a worker
+
+	client.Proxy(toproxy, {
+		apply(ctx) {
+			// origin/source doesn't need to be preserved - it's null in the message event
+
+			ctx.args[0] = {
+				$scramjet$messagetype: "worker",
+				$scramjet$data: ctx.args[0],
+			};
+		},
+	});
 }
diff --git a/src/client/shared/event.ts b/src/client/shared/event.ts
index 982d7fe..a1a7ebf 100644
--- a/src/client/shared/event.ts
+++ b/src/client/shared/event.ts
@@ -23,6 +23,8 @@ export default function (client: ScramjetClient, self: Self) {
 				return this.ports;
 			},
 			source() {
+				if (this.source === null) return null;
+
 				const scram: ScramjetClient = this.source[SCRAMJETCLIENT];
 
 				if (scram) return scram.globalProxy;
@@ -33,7 +35,6 @@ export default function (client: ScramjetClient, self: Self) {
 				if (typeof this.data === "object" && "$scramjet$origin" in this.data)
 					return this.data.$scramjet$origin;
 
-				// then it must be from a worker, which we aren't currently rewriting
 				return client.url.origin;
 			},
 			data() {
diff --git a/src/client/shared/worker.ts b/src/client/shared/worker.ts
index b478b49..e64bd83 100644
--- a/src/client/shared/worker.ts
+++ b/src/client/shared/worker.ts
@@ -33,9 +33,16 @@ export default function (client: ScramjetClient, self: typeof globalThis) {
 
 			const worker = call();
 			const conn = new BareMuxConnection();
+
 			(async () => {
 				const port = await conn.getInnerPort();
-				worker.postMessage(port, [port]);
+				worker.postMessage(
+					{
+						$scramjet$type: "baremuxinit",
+						port,
+					},
+					[port]
+				);
 			})();
 		},
 	});