diff --git a/doc/api/stream.md b/doc/api/stream.md
index 10c68d9b4dd074..a421d4acb6dfa9 100644
--- a/doc/api/stream.md
+++ b/doc/api/stream.md
@@ -596,8 +596,8 @@ changes:
   not operating in object mode, `chunk` must be a string, `Buffer` or
   `Uint8Array`. For object mode streams, `chunk` may be any JavaScript value
   other than `null`.
-* `encoding` {string} The encoding, if `chunk` is a string. **Default:** `'utf8'`
-* `callback` {Function} Callback for when this chunk of data is flushed
+* `encoding` {string|null} The encoding, if `chunk` is a string. **Default:** `'utf8'`
+* `callback` {Function} Callback for when this chunk of data is flushed.
 * Returns: {boolean} `false` if the stream wishes for the calling code to
   wait for the `'drain'` event to be emitted before continuing to write
   additional data; otherwise `true`.