diff --git a/src/common.ts b/src/common.ts
index e7c75df9..17572649 100644
--- a/src/common.ts
+++ b/src/common.ts
@@ -39,16 +39,22 @@ export const GAXIOS_ERROR_SYMBOL = Symbol.for(`${pkg.name}-gaxios-error`);
 /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
 export class GaxiosError<T = any> extends Error {
   /**
-   * An Error code.
-   * See {@link https://nodejs.org/api/errors.html#errorcode error.code}
+   * An error code.
+   * Can be a system error code, DOMException error name, or any error's 'code' property where it is a `string`.
+   *
+   * @see {@link https://nodejs.org/api/errors.html#errorcode error.code}
+   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/DOMException#error_names DOMException#error_names}
    *
    * @example
    * 'ECONNRESET'
+   *
+   * @example
+   * 'TimeoutError'
    */
   code?: string;
   /**
    * An HTTP Status code.
-   * See {@link https://developer.mozilla.org/en-US/docs/Web/API/Response/status Response: status property}
+   * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/Response/status Response#status}
    *
    * @example
    * 500
diff --git a/src/gaxios.ts b/src/gaxios.ts
index 22770fe5..dba42b9d 100644
--- a/src/gaxios.ts
+++ b/src/gaxios.ts
@@ -395,17 +395,6 @@ export class Gaxios {
       ) as {} as ReadableStream;
     } else if (shouldDirectlyPassData) {
       opts.body = opts.data as BodyInit;
-
-      /**
-       * Used for backwards-compatibility.
-       *
-       * @deprecated we shouldn't infer Buffers as JSON
-       */
-      if ('Buffer' in globalThis && Buffer.isBuffer(opts.data)) {
-        if (!preparedHeaders.has('content-type')) {
-          preparedHeaders.set('content-type', 'application/json');
-        }
-      }
     } else if (typeof opts.data === 'object') {
       if (
         preparedHeaders.get('Content-Type') ===
diff --git a/test/test.getch.ts b/test/test.getch.ts
index c42f1dbf..8b987f9a 100644
--- a/test/test.getch.ts
+++ b/test/test.getch.ts
@@ -1158,20 +1158,18 @@ describe('🍂 defaults & instances', () => {
     assert.deepStrictEqual(res.data, {});
   });
 
-  it('should set content-type to application/json by default, for buffer', async () => {
-    const pkg = fs.readFileSync('./package.json');
-    const pkgJson = JSON.parse(pkg.toString('utf8'));
+  it('should not set a default content-type for buffers', async () => {
+    const jsonLike = '{}';
+    const data = Buffer.from(jsonLike);
     const scope = nock(url)
-      .matchHeader('content-type', 'application/json')
-      .post('/', pkgJson)
-      .reply(200, {});
-    const res = await request({
-      url,
-      method: 'POST',
-      data: pkg,
-    });
+      // no content type should be present
+      .matchHeader('content-type', v => v === undefined)
+      .post('/', jsonLike)
+      .reply(204);
+
+    const res = await request({url, method: 'POST', data});
     scope.done();
-    assert.deepStrictEqual(res.data, {});
+    assert.equal(res.status, 204);
   });
 
   describe('mtls', () => {