diff --git a/tests/unit/blob_test.ts b/tests/unit/blob_test.ts
index 9de5b4ca302ec1..b89f4703e20ea5 100644
--- a/tests/unit/blob_test.ts
+++ b/tests/unit/blob_test.ts
@@ -85,7 +85,7 @@ Deno.test(async function blobStream() {
   const read = async (): Promise<void> => {
     const { done, value } = await reader.read();
     if (!done && value) {
-      bytes = concat([bytes, value]) as Uint8Array<ArrayBuffer>;
+      bytes = concat([bytes, value]);
       return read();
     }
   };
diff --git a/tests/unit/test_util.ts b/tests/unit/test_util.ts
index 0e5523b81a5eb4..6e7865ea7a43d4 100644
--- a/tests/unit/test_util.ts
+++ b/tests/unit/test_util.ts
@@ -22,6 +22,7 @@ export {
   unreachable,
 } from "@std/assert";
 export { delay } from "@std/async/delay";
+export { readLines } from "@std/io/read-lines";
 export { parseArgs } from "@std/cli/parse-args";
 
 export function pathToAbsoluteFileUrl(path: string): URL {
diff --git a/tests/unit/tls_test.ts b/tests/unit/tls_test.ts
index 48c3a04c77a286..53db347a131a8d 100644
--- a/tests/unit/tls_test.ts
+++ b/tests/unit/tls_test.ts
@@ -7,7 +7,7 @@ import {
   assertStrictEquals,
   assertThrows,
 } from "./test_util.ts";
-import { Buffer } from "@std/streams/buffer";
+import { BufReader, BufWriter } from "@std/io";
 import { readAll } from "@std/io/read-all";
 import { writeAll } from "@std/io/write-all";
 import { TextProtoReader } from "../testdata/run/textproto.ts";
@@ -114,11 +114,12 @@ Deno.test(
     );
 
     const conn = await Deno.connectTls({ hostname, port, caCerts });
-    const buffer = new Buffer(conn);
-    const w = buffer.writable.getWriter();
-    const r = buffer.readable.getWriter();
+    const w = new BufWriter(conn);
+    const r = new BufReader(conn);
     const body = `GET / HTTP/1.1\r\nHost: ${hostname}:${port}\r\n\r\n`;
-    await w.write(encoder.encode(body));
+    const writeResult = await w.write(encoder.encode(body));
+    assertEquals(body.length, writeResult);
+    await w.flush();
     const tpr = new TextProtoReader(r);
     const statusLine = await tpr.readLine();
     assert(statusLine !== null, `line must be read: ${String(statusLine)}`);
diff --git a/tests/util/std b/tests/util/std
index c5d7930d5700db..ace6a0e99a71c4 160000
--- a/tests/util/std
+++ b/tests/util/std
@@ -1 +1 @@
-Subproject commit c5d7930d5700dbbbedea607f9cf3e50acdc33e2d
+Subproject commit ace6a0e99a71c42227723220bfe77d5a64cd40a0