diff --git a/README.md b/README.md
index 9480032..a693c27 100644
--- a/README.md
+++ b/README.md
@@ -43,7 +43,7 @@ You can also call ncp like `ncp(source, destination, options, callback)`.
   parameter: copied file name, returning `true` or `false`, determining
   whether to copy file or not.
 
-  * `options.transform` - a function: `function (read, write) { read.pipe(write) }`
+  * `options.transform` - a function: `function (read, write, file) { read.pipe(write) }`
   used to apply streaming transforms while copying.
 
   * `options.clobber` - boolean=true. if set to false, `ncp` will not overwrite