diff --git a/README.md b/README.md
index 1e28ee6..eade082 100644
--- a/README.md
+++ b/README.md
@@ -108,7 +108,7 @@ Using an `Object` as the destination:
 
 ##### Methods
 
-###### transform(sourceValue, sourceObject, destinationObject, destinationKey);
+###### transform(sourceValue, sourceObject, destinationObject, sourceKey, destinationKey);
 
 Specify the mapping of a **sourceValue** as you need;