diff --git a/doc/api/buffer.md b/doc/api/buffer.md
index 2b63b4eb2e13f2..1ed15e28d50c7c 100644
--- a/doc/api/buffer.md
+++ b/doc/api/buffer.md
@@ -1177,8 +1177,12 @@ console.log(Buffer.allocUnsafe(3).fill('\u0222'));
 // Prints: <Buffer c8 a2 c8>
 ```
 
-If `value` contains invalid characters, it is truncated; if no valid
-fill data remains, no filling is performed:
+If `value` contains invalid characters, it is truncated.
+
+If no valid fill data remains, then the buffer is either zero-filled or no
+filling is performed, depending on the input type. That behavior is dictated by
+compatibility reasons and was changed to throwing an exception in Node.js v10,
+so it's not recommended to rely on that.
 
 ```js
 const buf = Buffer.allocUnsafe(5);