diff --git a/op_crates/websocket/01_websocket.js b/op_crates/websocket/01_websocket.js
index 374d174b02..c77af4566a 100644
--- a/op_crates/websocket/01_websocket.js
+++ b/op_crates/websocket/01_websocket.js
@@ -326,9 +326,9 @@
             let data;
 
             if (this.binaryType === "blob") {
-              data = new Blob([new Uint8Array(value)]);
+              data = new Blob([value]);
             } else {
-              data = new Uint8Array(value).buffer;
+              data = value.buffer;
             }
 
             const event = new MessageEvent("message", {
diff --git a/op_crates/websocket/lib.rs b/op_crates/websocket/lib.rs
index b81b1701d9..acf823775d 100644
--- a/op_crates/websocket/lib.rs
+++ b/op_crates/websocket/lib.rs
@@ -289,7 +289,7 @@ pub async fn op_ws_close(
 #[serde(tag = "kind", content = "value", rename_all = "camelCase")]
 pub enum NextEventResponse {
   String(String),
-  Binary(Vec<u8>),
+  Binary(ZeroCopyBuf),
   Close { code: u16, reason: String },
   Ping,
   Pong,
@@ -313,10 +313,7 @@ pub async fn op_ws_next_event(
   let val = rx.next().or_cancel(cancel).await?;
   let res = match val {
     Some(Ok(Message::Text(text))) => NextEventResponse::String(text),
-    Some(Ok(Message::Binary(data))) => {
-      // TODO(ry): don't use json to send binary data.
-      NextEventResponse::Binary(data)
-    }
+    Some(Ok(Message::Binary(data))) => NextEventResponse::Binary(data.into()),
     Some(Ok(Message::Close(Some(frame)))) => NextEventResponse::Close {
       code: frame.code.into(),
       reason: frame.reason.to_string(),