diff --git a/packages/metro-bundler/src/ModuleGraph/node-haste/Module.js b/packages/metro-bundler/src/ModuleGraph/node-haste/Module.js
index 5d361df3..6e00ea6d 100644
--- a/packages/metro-bundler/src/ModuleGraph/node-haste/Module.js
+++ b/packages/metro-bundler/src/ModuleGraph/node-haste/Module.js
@@ -13,10 +13,10 @@
 
 import type {CachedReadResult, ReadResult} from '../../node-haste/Module';
 import type {TransformedCodeFile} from '../types.flow';
-import type {ModuleCache} from './node-haste.flow';
+import type ModuleCache from './ModuleCache';
 
 module.exports = class Module {
-  hasteID: Promise<?string>;
+  hasteID: ?string;
   moduleCache: ModuleCache;
   name: Promise<string>;
   path: string;
@@ -27,9 +27,9 @@ module.exports = class Module {
     moduleCache: ModuleCache,
     info: TransformedCodeFile,
   ) {
-    this.hasteID = Promise.resolve(info.hasteID);
+    this.hasteID = info.hasteID;
     this.moduleCache = moduleCache;
-    this.name = this.hasteID.then(name => name || getName(path));
+    this.name = Promise.resolve(this.hasteID || getName(path));
     this.path = path;
     this.type = 'Module';
   }
@@ -51,7 +51,7 @@ module.exports = class Module {
   }
 
   isHaste() {
-    return this.hasteID.then(Boolean);
+    return Boolean(this.hasteID);
   }
 
   hash() {
diff --git a/packages/metro-bundler/src/ModuleGraph/node-haste/ModuleCache.js b/packages/metro-bundler/src/ModuleGraph/node-haste/ModuleCache.js
index 73bda233..0062e32d 100644
--- a/packages/metro-bundler/src/ModuleGraph/node-haste/ModuleCache.js
+++ b/packages/metro-bundler/src/ModuleGraph/node-haste/ModuleCache.js
@@ -34,11 +34,11 @@ module.exports = class ModuleCache {
     this.packages = new Map();
   }
 
-  getAssetModule(path: string) {
+  getAssetModule(path: string): Module {
     return this.getModule(path);
   }
 
-  getModule(path: string) {
+  getModule(path: string): Module {
     let m = this.modules.get(path);
     if (!m) {
       m = new Module(path, this, this.getTransformedFile(path));
@@ -47,7 +47,7 @@ module.exports = class ModuleCache {
     return m;
   }
 
-  getPackage(path: string) {
+  getPackage(path: string): Package {
     let p = this.packages.get(path);
     if (!p) {
       p = new Package(path, this.getPackageData(path));
@@ -64,7 +64,7 @@ module.exports = class ModuleCache {
     return pkg;
   }
 
-  getPackageOf(filePath: string) {
+  getPackageOf(filePath: string): ?Package {
     const candidate = this._getClosestPackage(filePath);
     return candidate != null ? this.getPackage(candidate) : null;
   }
diff --git a/packages/metro-bundler/src/ModuleGraph/node-haste/Package.js b/packages/metro-bundler/src/ModuleGraph/node-haste/Package.js
index 0f8ca641..c6f42d45 100644
--- a/packages/metro-bundler/src/ModuleGraph/node-haste/Package.js
+++ b/packages/metro-bundler/src/ModuleGraph/node-haste/Package.js
@@ -49,12 +49,12 @@ module.exports = class Package {
     return path.join(this.root, main);
   }
 
-  getName() {
+  getName(): Promise<string> {
     return Promise.resolve(nullthrows(this.data.name));
   }
 
-  isHaste() {
-    return Promise.resolve(!!this.data.name);
+  isHaste(): boolean {
+    return !!this.data.name;
   }
 
   redirectRequire(name: string) {
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 38fc8799..26c008f3 100644
--- a/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js
+++ b/packages/metro-bundler/src/ModuleGraph/node-haste/node-haste.js
@@ -31,6 +31,8 @@ const ResolutionRequest = require('../../node-haste/DependencyGraph/ResolutionRe
 
 const defaults = require('../../../defaults');
 
+import type {Moduleish, Packageish} from '../../node-haste/DependencyGraph/ResolutionRequest';
+
 type ResolveOptions = {|
   assetExts: Extensions,
   extraNodeModules: {[id: string]: string},
@@ -45,7 +47,7 @@ const platforms = new Set(defaults.platforms);
  * a jest-haste-map's ModuleMap instance. Eventually, though, we'll
  * want to figure out how to reunify and get rid of `HasteMap`.
  */
-function getFakeModuleMap(hasteMap: HasteMap) {
+function getFakeModuleMap(hasteMap: HasteMap<Module, Packageish>) {
   return {
     getModule(name: string, platform: ?string): ?string {
       const module = hasteMap.getModule(name, platform);
@@ -58,7 +60,7 @@ function getFakeModuleMap(hasteMap: HasteMap) {
   };
 }
 
-const nullModule = {
+const nullModule: Moduleish = {
   path: '/',
   getPackage() {},
   hash() {
@@ -66,6 +68,8 @@ const nullModule = {
   },
   readCached() { throw new Error('not implemented'); },
   readFresh() { return Promise.reject(new Error('not implemented')); },
+  isHaste() { throw new Error('not implemented'); },
+  getName() { throw new Error('not implemented'); },
 };
 
 exports.createResolveFn = function(options: ResolveOptions): ResolveFn {
diff --git a/packages/metro-bundler/src/node-haste/DependencyGraph/HasteMap.js b/packages/metro-bundler/src/node-haste/DependencyGraph/HasteMap.js
index 6201fb94..262efb18 100644
--- a/packages/metro-bundler/src/node-haste/DependencyGraph/HasteMap.js
+++ b/packages/metro-bundler/src/node-haste/DependencyGraph/HasteMap.js
@@ -5,7 +5,11 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
+ * @format
  */
+
 'use strict';
 
 const EventEmitter = require('events');
@@ -18,15 +22,37 @@ const GENERIC_PLATFORM = 'generic';
 const NATIVE_PLATFORM = 'native';
 const PACKAGE_JSON = path.sep + 'package.json';
 
-class HasteMap extends EventEmitter {
+import type {Moduleish, Packageish, ModuleishCache} from './ResolutionRequest';
+import type DependencyGraphHelpers from './DependencyGraphHelpers';
+
+type Options<TModule, TPackage> = {|
+  extensions: Array<string>,
+  files: Array<string>,
+  helpers: DependencyGraphHelpers,
+  moduleCache: ModuleishCache<TModule, TPackage>,
+  platforms: Set<string>,
+  preferNativePlatform: boolean,
+|};
+
+class HasteMap<TModule: Moduleish, TPackage: Packageish> extends EventEmitter {
+
+  _extensions: Array<string>;
+  _files: Array<string>;
+  _helpers: DependencyGraphHelpers;
+  _map: {};
+  _moduleCache: ModuleishCache<TModule, TPackage>;
+  _packages: {};
+  _platforms: Set<string>;
+  _preferNativePlatform: boolean;
+
   constructor({
     extensions,
     files,
-    moduleCache,
-    preferNativePlatform,
     helpers,
+    moduleCache,
     platforms,
-  }) {
+    preferNativePlatform,
+  }: Options<TModule, TPackage>) {
     super();
     this._extensions = extensions;
     this._files = files;
@@ -35,8 +61,8 @@ class HasteMap extends EventEmitter {
     this._platforms = platforms;
     this._preferNativePlatform = preferNativePlatform;
 
-    this._processHastePackage = throat(1, this._processHastePackage.bind(this));
-    this._processHasteModule = throat(1, this._processHasteModule.bind(this));
+    (this: any)._processHastePackage = throat(1, this._processHastePackage.bind(this));
+    (this: any)._processHasteModule = throat(1, this._processHasteModule.bind(this));
   }
 
   build() {
@@ -60,7 +86,7 @@ class HasteMap extends EventEmitter {
     return this._files;
   }
 
-  processFileChange(type, absPath) {
+  processFileChange(type: string, absPath: string) {
     return Promise.resolve().then(() => {
       /*eslint no-labels: 0 */
       let invalidated;
@@ -96,7 +122,7 @@ class HasteMap extends EventEmitter {
     });
   }
 
-  getModule(name, platform = null): Module {
+  getModule(name: string, platform: ?string): ?TModule {
     const modulesMap = this._map[name];
     if (modulesMap == null) {
       return null;
@@ -117,11 +143,11 @@ class HasteMap extends EventEmitter {
     return module;
   }
 
-  getPackage(name): Package {
+  getPackage(name: string): TPackage {
     return this._packages[name];
   }
 
-  _processHasteModule(file, previousName) {
+  _processHasteModule(file: string, previousName: ?string) {
     const module = this._moduleCache.getModule(file);
     return Promise.resolve().then(() => {
       const isHaste = module.isHaste();
@@ -136,7 +162,7 @@ class HasteMap extends EventEmitter {
     });
   }
 
-  _processHastePackage(file, previousName) {
+  _processHastePackage(file: string, previousName: ?string) {
     const p = this._moduleCache.getPackage(file);
     return Promise.resolve().then(() => {
       const isHaste = p.isHaste();
@@ -157,7 +183,7 @@ class HasteMap extends EventEmitter {
     });
   }
 
-  _updateHasteMap(name, mod) {
+  _updateHasteMap(name: string, mod: TModule | TPackage) {
     let existingModule;
 
     if (mod.type === 'Package') {
diff --git a/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js b/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
index 7118f545..5178d693 100644
--- a/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
+++ b/packages/metro-bundler/src/node-haste/DependencyGraph/ResolutionRequest.js
@@ -49,21 +49,26 @@ export type ModuleMap = {
   ): ?string,
 };
 
-type Packageish = {
+export type Packageish = {
+  isHaste(): boolean,
+  getName(): Promise<string>,
+  path: string,
   redirectRequire(toModuleName: string): string | false,
   getMain(): string,
   +root: string,
 };
 
-type Moduleish = {
+export type Moduleish = {
   +path: string,
+  isHaste(): boolean,
+  getName(): Promise<string>,
   getPackage(): ?Packageish,
   hash(): string,
   readCached(transformOptions: TransformWorkerOptions): CachedReadResult,
   readFresh(transformOptions: TransformWorkerOptions): Promise<ReadResult>,
 };
 
-type ModuleishCache<TModule, TPackage> = {
+export type ModuleishCache<TModule, TPackage> = {
   getPackage(
     name: string,
     platform?: string,
diff --git a/packages/metro-bundler/src/node-haste/Package.js b/packages/metro-bundler/src/node-haste/Package.js
index 6e3f3efb..01904704 100644
--- a/packages/metro-bundler/src/node-haste/Package.js
+++ b/packages/metro-bundler/src/node-haste/Package.js
@@ -59,8 +59,8 @@ class Package {
     return path.join(this.root, main);
   }
 
-  isHaste(): Promise<boolean> {
-    return Promise.resolve().then(() => !!this.read().name);
+  isHaste(): boolean {
+    return !!this.read().name;
   }
 
   getName(): Promise<string> {