diff --git a/packager/react-packager/src/AssetServer/__tests__/AssetServer-test.js b/packager/react-packager/src/AssetServer/__tests__/AssetServer-test.js
index ba804b5f1..43f223453 100644
--- a/packager/react-packager/src/AssetServer/__tests__/AssetServer-test.js
+++ b/packager/react-packager/src/AssetServer/__tests__/AssetServer-test.js
@@ -1,10 +1,13 @@
 'use strict';
 
 jest
-  .dontMock('path')
   .dontMock('../../lib/getAssetDataFromName')
   .dontMock('../');
 
+jest
+  .mock('crypto')
+  .mock('fs');
+
 var Promise = require('bluebird');
 
 describe('AssetServer', function() {
diff --git a/packager/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js b/packager/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
index 9cb08122c..f75445d09 100644
--- a/packager/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
+++ b/packager/react-packager/src/DependencyResolver/haste/DependencyGraph/__tests__/DependencyGraph-test.js
@@ -10,13 +10,14 @@
 
 jest
   .dontMock('../index')
-  .dontMock('path')
   .dontMock('absolute-path')
   .dontMock('../docblock')
   .dontMock('../../replacePatterns')
   .dontMock('../../../../lib/getAssetDataFromName')
   .setMock('../../../ModuleDescriptor', function(data) {return data;});
 
+jest.mock('fs');
+
 describe('DependencyGraph', function() {
   var DependencyGraph;
   var fileWatcher;
diff --git a/packager/react-packager/src/DependencyResolver/haste/__tests__/HasteDependencyResolver-test.js b/packager/react-packager/src/DependencyResolver/haste/__tests__/HasteDependencyResolver-test.js
index b3063cb57..9bc8b8b95 100644
--- a/packager/react-packager/src/DependencyResolver/haste/__tests__/HasteDependencyResolver-test.js
+++ b/packager/react-packager/src/DependencyResolver/haste/__tests__/HasteDependencyResolver-test.js
@@ -13,6 +13,8 @@ jest.dontMock('../')
     .dontMock('../replacePatterns')
     .setMock('../../ModuleDescriptor', function(data) {return data;});
 
+jest.mock('path');
+
 var Promise = require('bluebird');
 
 describe('HasteDependencyResolver', function() {
diff --git a/packager/react-packager/src/JSTransformer/__tests__/Cache-test.js b/packager/react-packager/src/JSTransformer/__tests__/Cache-test.js
index 51f7ec05e..7ad658183 100644
--- a/packager/react-packager/src/JSTransformer/__tests__/Cache-test.js
+++ b/packager/react-packager/src/JSTransformer/__tests__/Cache-test.js
@@ -10,11 +10,13 @@
 
 jest
   .dontMock('underscore')
-  .dontMock('path')
   .dontMock('absolute-path')
-  .dontMock('crypto')
   .dontMock('../Cache');
 
+jest
+  .mock('os')
+  .mock('fs');
+
 var Promise = require('bluebird');
 
 describe('JSTransformer Cache', function() {
diff --git a/packager/react-packager/src/JSTransformer/__tests__/Transformer-test.js b/packager/react-packager/src/JSTransformer/__tests__/Transformer-test.js
index eb307a02e..5948916a7 100644
--- a/packager/react-packager/src/JSTransformer/__tests__/Transformer-test.js
+++ b/packager/react-packager/src/JSTransformer/__tests__/Transformer-test.js
@@ -10,10 +10,11 @@
 
 jest
   .dontMock('worker-farm')
-  .dontMock('os')
   .dontMock('../../lib/ModuleTransport')
   .dontMock('../index');
 
+jest.mock('fs');
+
 var OPTIONS = {
   transformModulePath: '/foo/bar'
 };
diff --git a/packager/react-packager/src/Packager/__tests__/Packager-test.js b/packager/react-packager/src/Packager/__tests__/Packager-test.js
index d4a1c0f36..9babda547 100644
--- a/packager/react-packager/src/Packager/__tests__/Packager-test.js
+++ b/packager/react-packager/src/Packager/__tests__/Packager-test.js
@@ -10,13 +10,13 @@
 
 jest
   .setMock('worker-farm', function() { return function() {};})
-  .dontMock('path')
-  .dontMock('os')
   .dontMock('underscore')
   .dontMock('../../lib/ModuleTransport')
   .setMock('uglify-js')
   .dontMock('../');
 
+jest.mock('fs');
+
 var Promise = require('bluebird');
 
 describe('Packager', function() {