diff --git a/packager/react-packager/src/node-haste/AssetModule.js b/packager/react-packager/src/node-haste/AssetModule.js
index 97e0c840b..21a12ef23 100644
--- a/packager/react-packager/src/node-haste/AssetModule.js
+++ b/packager/react-packager/src/node-haste/AssetModule.js
@@ -5,15 +5,26 @@
  * 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
  */
+
 'use strict';
 
 const Module = require('./Module');
 
 const getAssetDataFromName = require('./lib/getAssetDataFromName');
 
+import type {ConstructorArgs, ReadResult} from './Module';
+
 class AssetModule extends Module {
-  constructor(args, platforms) {
+
+  resolution: mixed;
+  _name: string;
+  _type: string;
+  _dependencies: Array<string>;
+
+  constructor(args: ConstructorArgs & {dependencies: Array<string>}, platforms: Set<string>) {
     super(args);
     const { resolution, name, type } = getAssetDataFromName(this.path, platforms);
     this.resolution = resolution;
@@ -30,7 +41,9 @@ class AssetModule extends Module {
     return Promise.resolve(this._dependencies);
   }
 
-  read() {
+  read(): Promise<ReadResult> {
+    /** $FlowFixMe: improper OOP design. AssetModule, being different from a
+     * normal Module, shouldn't inherit it in the first place. */
     return Promise.resolve({});
   }
 
diff --git a/packager/react-packager/src/node-haste/Module.js b/packager/react-packager/src/node-haste/Module.js
index b4479ee07..43d4c3197 100644
--- a/packager/react-packager/src/node-haste/Module.js
+++ b/packager/react-packager/src/node-haste/Module.js
@@ -31,7 +31,7 @@ import type Cache from './Cache';
 import type DependencyGraphHelpers from './DependencyGraph/DependencyGraphHelpers';
 import type ModuleCache from './ModuleCache';
 
-type ReadResult = {
+export type ReadResult = {
   code: string,
   dependencies?: ?Array<string>,
   dependencyOffsets?: ?Array<number>,
diff --git a/packager/react-packager/src/node-haste/ModuleCache.js b/packager/react-packager/src/node-haste/ModuleCache.js
index 94358a3c4..193dac4df 100644
--- a/packager/react-packager/src/node-haste/ModuleCache.js
+++ b/packager/react-packager/src/node-haste/ModuleCache.js
@@ -28,7 +28,7 @@ type GetClosestPackageFn = (filePath: string) => ?string;
 
 class ModuleCache {
 
-  _assetDependencies: mixed;
+  _assetDependencies: Array<string>;
   _cache: Cache;
   _depGraphHelpers: DependencyGraphHelpers;
   _getClosestPackage: GetClosestPackageFn;
@@ -36,7 +36,7 @@ class ModuleCache {
   _moduleOptions: ModuleOptions;
   _packageCache: {[filePath: string]: Package};
   _packageModuleMap: WeakMap<Module, string>;
-  _platforms: mixed;
+  _platforms: Set<string>;
   _transformCacheKey: string;
   _transformCode: TransformCode;
   _reporter: Reporter;
@@ -52,7 +52,7 @@ class ModuleCache {
     transformCode,
     reporter,
   }: {
-    assetDependencies: mixed,
+    assetDependencies: Array<string>,
     cache: Cache,
     depGraphHelpers: DependencyGraphHelpers,
     getClosestPackage: GetClosestPackageFn,
@@ -60,7 +60,7 @@ class ModuleCache {
     transformCacheKey: string,
     transformCode: TransformCode,
     reporter: Reporter,
-  }, platforms: mixed) {
+  }, platforms: Set<string>) {
     this._assetDependencies = assetDependencies;
     this._getClosestPackage = getClosestPackage;
     this._cache = cache;
@@ -97,6 +97,9 @@ class ModuleCache {
 
   getAssetModule(filePath: string) {
     if (!this._moduleCache[filePath]) {
+      /* $FlowFixMe: missing options. This is because this is an incorrect OOP
+       * design in the first place: AssetModule, being simpler than a normal
+       * Module, should not inherit the Module class. */
       this._moduleCache[filePath] = new AssetModule({
         file: filePath,
         moduleCache: this,
diff --git a/packager/react-packager/src/node-haste/index.js b/packager/react-packager/src/node-haste/index.js
index 13ded6d58..a37f96279 100644
--- a/packager/react-packager/src/node-haste/index.js
+++ b/packager/react-packager/src/node-haste/index.js
@@ -68,7 +68,7 @@ class DependencyGraph {
     useWatchman: boolean,
     watch: boolean,
   |};
-  _assetDependencies: mixed;
+  _assetDependencies: Array<string>;
   _cache: Cache;
   _haste: JestHasteMap;
   _hasteFS: HasteFS;
@@ -103,7 +103,7 @@ class DependencyGraph {
     watch,
     reporter,
   }: {
-    assetDependencies: mixed,
+    assetDependencies: Array<string>,
     assetExts: Array<string>,
     cache: Cache,
     extensions?: ?Array<string>,