diff --git a/README.md b/README.md
index 1848657a..986acf9f 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,10 @@ npm install diff --save
 * `Diff.diffJson(oldObj, newObj[, options])` - diffs two JSON objects, comparing the fields defined on each. The order of fields, etc does not matter in this comparison.
 
     Returns a list of [change objects](#change-objects).
+    
+    Options
+    * `stringifyReplacer`: A custom replacer function. Operates similarly to the `replacer` parameter to [`JSON.stringify()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#the_replacer_parameter), but must be a function.
+    *  `undefinedReplacement`: A value to replace `undefined` with. Ignored if a `stringifyReplacer` is provided.
 
 * `Diff.diffArrays(oldArr, newArr[, options])` - diffs two arrays, comparing each item for strict equality (===).