diff --git a/doc/api/stream.md b/doc/api/stream.md
index 10b302359abcfa..b698cb6cfe634a 100644
--- a/doc/api/stream.md
+++ b/doc/api/stream.md
@@ -4507,7 +4507,8 @@ The `callback` function must be called only when the current chunk is completely
 consumed. The first argument passed to the `callback` must be an `Error` object
 if an error occurred while processing the input or `null` otherwise. If a second
 argument is passed to the `callback`, it will be forwarded on to the
-`transform.push()` method. In other words, the following are equivalent:
+`transform.push()` method, but only if the first argument is falsy. In other
+words, the following are equivalent:
 
 ```js
 transform.prototype._transform = function(data, encoding, callback) {