diff --git a/file/README.md b/file/README.md
index ee93e4f..8be9c96 100644
--- a/file/README.md
+++ b/file/README.md
@@ -15,7 +15,7 @@ Navigates a file tree, calling callback for each directory, passing in (null, di
 
 ### file.walkSync(start, callback)
 
-Like file.walk but synchronous.
+Like file.walk but synchronous. Callback is passed (dirPath, dirs, files).
 
 
 ### file.mkdirs(path, callback)