diff --git a/lib/fs.js b/lib/fs.js
index 6a456bcd5acffb..256098cd213a4c 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -2379,6 +2379,7 @@ function writeFileSync(path, data, options) {
  *   encoding?: string | null;
  *   mode?: number;
  *   flag?: string;
+ *   flush?: boolean;
  *   } | string} [options]
  * @param {(err?: Error) => any} callback
  * @returns {void}
diff --git a/lib/internal/fs/promises.js b/lib/internal/fs/promises.js
index 626ee8ad3f942f..bdefea99edfe3c 100644
--- a/lib/internal/fs/promises.js
+++ b/lib/internal/fs/promises.js
@@ -354,6 +354,7 @@ class FileHandle extends EventEmitterMixin(JSTransferable) {
    *   autoClose?: boolean;
    *   emitClose?: boolean;
    *   start: number;
+   *   highWaterMark?: number;
    *   flush?: boolean;
    *   }} [options]
    * @returns {WriteStream}