diff --git a/packages/metro-bundler/src/ModuleGraph/Graph.js b/packages/metro-bundler/src/ModuleGraph/Graph.js
index 27288c31..e8079139 100644
--- a/packages/metro-bundler/src/ModuleGraph/Graph.js
+++ b/packages/metro-bundler/src/ModuleGraph/Graph.js
@@ -46,7 +46,7 @@ type Async$Queue<T, C> = {
 };
 
 type LoadQueue =
-  Async$Queue<{id: string, parent: string}, Callback<File, Array<string>>>;
+  Async$Queue<{id: string, parent: ?string}, Callback<File, Array<string>>>;
 
 const createParentModule =
   () => ({file: {code: '', type: 'script', path: ''}, dependencies: []});
@@ -57,7 +57,6 @@ const NO_OPTIONS = {};
 exports.create = function create(resolve: ResolveFn, load: LoadFn): GraphFn {
   function Graph(entryPoints, platform, options, callback = noop) {
     const {
-      cwd = '',
       log = (console: any),
       optimize = false,
       skip,
@@ -74,7 +73,7 @@ exports.create = function create(resolve: ResolveFn, load: LoadFn): GraphFn {
       memoize((file, cb) => load(file, {log, optimize}, cb)),
     ), Number.MAX_SAFE_INTEGER);
 
-    const {collect, loadModule} = createGraphHelpers(loadQueue, cwd, skip);
+    const {collect, loadModule} = createGraphHelpers(loadQueue, skip);
 
     loadQueue.drain = () => {
       loadQueue.kill();
@@ -101,7 +100,7 @@ exports.create = function create(resolve: ResolveFn, load: LoadFn): GraphFn {
   return Graph;
 };
 
-function createGraphHelpers(loadQueue, cwd, skip) {
+function createGraphHelpers(loadQueue, skip) {
   const modules = new Map([[null, createParentModule()]]);
 
   function collect(
@@ -132,7 +131,7 @@ function createGraphHelpers(loadQueue, cwd, skip) {
 
   function loadModule(id, parent, parentDepIndex) {
     loadQueue.push(
-      {id, parent: parent != null ? parent : cwd},
+      {id, parent},
       (error, file, dependencyIDs) =>
         onFileLoaded(error, file, dependencyIDs, id, parent, parentDepIndex),
     );
diff --git a/packages/metro-bundler/src/ModuleGraph/__tests__/Graph-test.js b/packages/metro-bundler/src/ModuleGraph/__tests__/Graph-test.js
index 621f489d..032bd3fd 100644
--- a/packages/metro-bundler/src/ModuleGraph/__tests__/Graph-test.js
+++ b/packages/metro-bundler/src/ModuleGraph/__tests__/Graph-test.js
@@ -46,7 +46,7 @@ describe('Graph:', () => {
     const entryPoint = '/arbitrary/path';
     graph([entryPoint], anyPlatform, noOpts, () => {
       expect(resolve).toBeCalledWith(
-        entryPoint, '', any(String), any(Object), any(Function));
+        entryPoint, null, any(String), any(Object), any(Function));
       done();
     });
   });
@@ -55,9 +55,9 @@ describe('Graph:', () => {
     const entryPoints = ['Arbitrary', '../entry.js'];
     graph(entryPoints, anyPlatform, noOpts, () => {
       expect(resolve).toBeCalledWith(
-        entryPoints[0], '', any(String), any(Object), any(Function));
+        entryPoints[0], null, any(String), any(Object), any(Function));
       expect(resolve).toBeCalledWith(
-        entryPoints[1], '', any(String), any(Object), any(Function));
+        entryPoints[1], null, any(String), any(Object), any(Function));
       done();
     });
 
@@ -74,7 +74,7 @@ describe('Graph:', () => {
     const platform = 'any';
     graph(anyEntry, platform, noOpts, () => {
       expect(resolve).toBeCalledWith(
-        any(String), '', platform, any(Object), any(Function));
+        any(String), null, platform, any(Object), any(Function));
       done();
     });
   });
@@ -83,7 +83,7 @@ describe('Graph:', () => {
     const log = new Console();
     graph(anyEntry, anyPlatform, {log}, () => {
       expect(resolve).toBeCalledWith(
-        any(String), '', any(String), objectContaining({log}), any(Function));
+        any(String), null, any(String), objectContaining({log}), any(Function));
       done();
     });
   });
diff --git a/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js b/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js
index 3481185b..daf739a7 100644
--- a/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js
+++ b/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js
@@ -102,7 +102,7 @@ exports.createResolveFn = function(options: ResolveOptions): ResolveFn {
   const hasteMapBuilt = hasteMap.build();
   const resolutionRequests = {};
   const filesByDirNameIndex = new FilesByDirNameIndex(hasteMap.getAllFiles());
-  return (id, source: ?string, platform, _, callback) => {
+  return (id, source, platform, _, callback) => {
     let resolutionRequest = resolutionRequests[platform];
     if (!resolutionRequest) {
       resolutionRequest = resolutionRequests[platform] = new ResolutionRequest({
diff --git a/packages/metro-bundler/src/ModuleGraph/types.flow.js b/packages/metro-bundler/src/ModuleGraph/types.flow.js
index 2c0c038c..4e8643b8 100644
--- a/packages/metro-bundler/src/ModuleGraph/types.flow.js
+++ b/packages/metro-bundler/src/ModuleGraph/types.flow.js
@@ -40,7 +40,6 @@ export type GraphFn = (
 ) => void;
 
 type GraphOptions = {|
-  cwd?: string,
   log?: Console,
   optimize?: boolean,
   skip?: Set<string>,
@@ -90,7 +89,7 @@ export type PackageData = {|
 
 export type ResolveFn = (
   id: string,
-  source: string,
+  source: ?string,
   platform: string,
   options?: ResolveOptions,
   callback: Callback<string>,