diff --git a/src/index.cc b/src/index.cc
index f54f9c790..191c6ccfe 100644
--- a/src/index.cc
+++ b/src/index.cc
@@ -771,12 +771,6 @@ Handle<Value> GitIndex::IndexToWorkdir(const Arguments& args) {
       if (args.Length() == 0 || !args[0]->IsObject()) {
     return ThrowException(Exception::Error(String::New("Repository repo is required.")));
   }
-  if (args.Length() == 1 || !args[1]->IsObject()) {
-    return ThrowException(Exception::Error(String::New("Index index is required.")));
-  }
-  if (args.Length() == 2 || !args[2]->IsObject()) {
-    return ThrowException(Exception::Error(String::New("DiffOptions opts is required.")));
-  }
 
   if (args.Length() == 3 || !args[3]->IsFunction()) {
     return ThrowException(Exception::Error(String::New("Callback is required and must be a Function.")));
@@ -792,12 +786,20 @@ Handle<Value> GitIndex::IndexToWorkdir(const Arguments& args) {
           baton->repo = from_repo;
     baton->indexReference = Persistent<Value>::New(args[1]);
     git_index * from_index;
+      if (args[1]->IsObject()) {
             from_index = ObjectWrap::Unwrap<GitIndex>(args[1]->ToObject())->GetValue();
-          baton->index = from_index;
+          } else {
+      from_index = 0;
+    }
+      baton->index = from_index;
     baton->optsReference = Persistent<Value>::New(args[2]);
     const git_diff_options * from_opts;
+      if (args[2]->IsObject()) {
             from_opts = ObjectWrap::Unwrap<GitDiffOptions>(args[2]->ToObject())->GetValue();
-          baton->opts = from_opts;
+          } else {
+      from_opts = 0;
+    }
+      baton->opts = from_opts;
     baton->callback = Persistent<Function>::New(Local<Function>::Cast(args[3]));
 
   uv_queue_work(uv_default_loop(), &baton->request, IndexToWorkdirWork, (uv_after_work_cb)IndexToWorkdirAfterWork);
diff --git a/v0.18.0.json b/v0.18.0.json
index 9ae029ae2..5c800ca1d 100644
--- a/v0.18.0.json
+++ b/v0.18.0.json
@@ -5439,6 +5439,7 @@
             "cType": "git_index *",
             "cppClassName": "GitIndex",
             "jsClassName": "Index",
+            "isOptional": true,
             "comment": "The index to diff from; repo index used if NULL."
           },
           {
@@ -5446,6 +5447,7 @@
             "cType": "const git_diff_options *",
             "cppClassName": "GitDiffOptions",
             "jsClassName": "DiffOptions",
+            "isOptional": true,
             "comment": "Structure with options to influence diff or NULL for defaults."
           }
         ],