diff --git a/lib/internal/webstreams/adapters.js b/lib/internal/webstreams/adapters.js
index 1ffb19b4f59a31..f7ecbed27384a3 100644
--- a/lib/internal/webstreams/adapters.js
+++ b/lib/internal/webstreams/adapters.js
@@ -56,7 +56,7 @@ const {
 } = require('buffer');
 
 const {
-  isArrayBuffer,
+  isAnyArrayBuffer,
 } = require('internal/util/types');
 
 const {
@@ -230,11 +230,11 @@ function newWritableStreamFromStreamWritable(streamWritable, options = kEmptyObj
     start(c) { controller = c; },
 
     write(chunk) {
-      if (!streamWritable.writableObjectMode && isArrayBuffer(chunk)) {
-        chunk = new Uint8Array(chunk);
-      }
       try {
         options[kValidateChunk]?.(chunk);
+        if (!streamWritable.writableObjectMode && isAnyArrayBuffer(chunk)) {
+          chunk = new Uint8Array(chunk);
+        }
         if (streamWritable.writableNeedDrain || !streamWritable.write(chunk)) {
           backpressurePromise = PromiseWithResolvers();
           return SafePromisePrototypeFinally(
diff --git a/lib/internal/webstreams/compression.js b/lib/internal/webstreams/compression.js
index 7ec929d94a0da0..70359d1158eee8 100644
--- a/lib/internal/webstreams/compression.js
+++ b/lib/internal/webstreams/compression.js
@@ -40,7 +40,7 @@ function lazyZlib() {
 // Per the Compression Streams spec, chunks must be BufferSource
 // (ArrayBuffer or ArrayBufferView not backed by SharedArrayBuffer).
 function validateBufferSourceChunk(chunk) {
-  if (isArrayBufferView(chunk) && isSharedArrayBuffer(chunk.buffer)) {
+  if (isSharedArrayBuffer(isArrayBufferView(chunk) ? chunk.buffer : chunk)) {
     throw new ERR_INVALID_ARG_TYPE(
       'chunk',
       ['ArrayBuffer', 'Buffer', 'TypedArray', 'DataView'],
diff --git a/test/parallel/test-webstreams-adapters-writable-buffer-sources.js b/test/parallel/test-webstreams-adapters-writable-buffer-sources.js
new file mode 100644
index 00000000000000..995db97e747364
--- /dev/null
+++ b/test/parallel/test-webstreams-adapters-writable-buffer-sources.js
@@ -0,0 +1,95 @@
+'use strict';
+const common = require('../common');
+
+const assert = require('assert');
+const { Buffer } = require('buffer');
+const { Duplex, Writable } = require('stream');
+const { suite, test } = require('node:test');
+
+const ctors = [ArrayBuffer, SharedArrayBuffer];
+
+suite('underlying Writable', () => {
+  suite('in non-object mode', () => {
+    for (const ctor of ctors) {
+      test(`converts ${ctor.name} chunks`, async () => {
+        const buffer = new ctor(4);
+        const writable = new Writable({
+          objectMode: false,
+          write: common.mustCall((chunk, encoding, callback) => {
+            assert(Buffer.isBuffer(chunk));
+            assert.strictEqual(chunk.buffer, buffer);
+            callback();
+          }),
+        });
+        writable.on('error', common.mustNotCall());
+        const writer = Writable.toWeb(writable).getWriter();
+        await writer.write(buffer);
+      });
+    }
+  });
+
+  suite('in object mode', () => {
+    for (const ctor of ctors) {
+      test(`passes through ${ctor.name} chunks`, async () => {
+        const buffer = new ctor(4);
+        const writable = new Writable({
+          objectMode: true,
+          write: common.mustCall((chunk, encoding, callback) => {
+            assert(chunk instanceof ctor);
+            assert.strictEqual(chunk, buffer);
+            callback();
+          }),
+        });
+        writable.on('error', common.mustNotCall());
+        const writer = Writable.toWeb(writable).getWriter();
+        await writer.write(buffer);
+      });
+    }
+  });
+});
+
+suite('underlying Duplex', () => {
+  suite('in non-object mode', () => {
+    for (const ctor of ctors) {
+      test(`converts ${ctor.name} chunks`, async () => {
+        const buffer = new ctor(4);
+        const duplex = new Duplex({
+          writableObjectMode: false,
+          write: common.mustCall((chunk, encoding, callback) => {
+            assert(Buffer.isBuffer(chunk));
+            assert.strictEqual(chunk.buffer, buffer);
+            callback();
+          }),
+          read() {
+            this.push(null);
+          },
+        });
+        duplex.on('error', common.mustNotCall());
+        const writer = Duplex.toWeb(duplex).writable.getWriter();
+        await writer.write(buffer);
+      });
+    }
+  });
+
+  suite('in object mode', () => {
+    for (const ctor of ctors) {
+      test(`passes through ${ctor.name} chunks`, async () => {
+        const buffer = new ctor(4);
+        const duplex = new Duplex({
+          writableObjectMode: true,
+          write: common.mustCall((chunk, encoding, callback) => {
+            assert(chunk instanceof ctor);
+            assert.strictEqual(chunk, buffer);
+            callback();
+          }),
+          read() {
+            this.push(null);
+          },
+        });
+        duplex.on('error', common.mustNotCall());
+        const writer = Duplex.toWeb(duplex).writable.getWriter();
+        await writer.write(buffer);
+      });
+    }
+  });
+});