diff --git a/packages/metro-bundler/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js b/packages/metro-bundler/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
index 95ca2ecd..438347a3 100644
--- a/packages/metro-bundler/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
+++ b/packages/metro-bundler/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
@@ -133,16 +133,19 @@ describe('traverseDependencies', function() {
     let DependencyGraph;
     let processDgraph;
     const consoleWarn = console.warn;
-    const realPlatform = process.platform;
     beforeEach(function() {
-      process.platform = 'linux';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'linux',
+      });
+
       DependencyGraph = require('../../node-haste/DependencyGraph');
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
     afterEach(function() {
       console.warn = consoleWarn;
-      process.platform = realPlatform;
     });
 
     it('should get dependencies', async () => {
@@ -2403,11 +2406,14 @@ describe('traverseDependencies', function() {
   });
 
   describe('get sync dependencies (win32)', () => {
-    const realPlatform = process.platform;
     let DependencyGraph;
     let processDgraph;
     beforeEach(function() {
-      process.platform = 'win32';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'win32',
+      });
 
       // reload path module
       jest.resetModules();
@@ -2416,10 +2422,6 @@ describe('traverseDependencies', function() {
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
-    afterEach(function() {
-      process.platform = realPlatform;
-    });
-
     it('should get dependencies', async () => {
       const root = 'C:\\root';
       setMockFileSystem({
@@ -2580,20 +2582,20 @@ describe('traverseDependencies', function() {
   });
 
   describe('node_modules (posix)', function() {
-    const realPlatform = process.platform;
     let DependencyGraph;
     let processDgraph;
 
     beforeEach(function() {
-      process.platform = 'linux';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'linux',
+      });
+
       DependencyGraph = require('../../node-haste/DependencyGraph');
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
-    afterEach(function() {
-      process.platform = realPlatform;
-    });
-
     it('should work with nested node_modules', async () => {
       var root = '/root';
       setMockFileSystem({
@@ -3524,11 +3526,15 @@ describe('traverseDependencies', function() {
   });
 
   describe('node_modules (win32)', function() {
-    const realPlatform = process.platform;
     let DependencyGraph;
     let processDgraph;
     beforeEach(() => {
-      process.platform = 'win32';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'win32',
+      });
+
       // reload path module
       jest.resetModules();
       jest.mock('path', () => require.requireActual('path').win32);
@@ -3536,10 +3542,6 @@ describe('traverseDependencies', function() {
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
-    afterEach(() => {
-      process.platform = realPlatform;
-    });
-
     it('should work with nested node_modules', async () => {
       var root = 'C:\\root';
       setMockFileSystem({
@@ -4424,20 +4426,20 @@ describe('traverseDependencies', function() {
   });
 
   describe('file watch updating', function() {
-    const realPlatform = process.platform;
     let DependencyGraph;
     let processDgraph;
 
     beforeEach(function() {
-      process.platform = 'linux';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'linux',
+      });
+
       DependencyGraph = require('../../node-haste/DependencyGraph');
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
-    afterEach(function() {
-      process.platform = realPlatform;
-    });
-
     it('updates module dependencies', async () => {
       var root = '/root';
       var filesystem = setMockFileSystem({
@@ -5092,20 +5094,20 @@ describe('traverseDependencies', function() {
   });
 
   describe('Extensions', () => {
-    const realPlatform = process.platform;
     let DependencyGraph;
     let processDgraph;
 
     beforeEach(function() {
-      process.platform = 'linux';
+      Object.defineProperty(process, 'platform', {
+        configurable: true,
+        enumerable: true,
+        value: 'linux',
+      });
+
       DependencyGraph = require('../../node-haste/DependencyGraph');
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
     });
 
-    afterEach(function() {
-      process.platform = realPlatform;
-    });
-
     it('supports custom file extensions', async () => {
       var root = '/root';
       setMockFileSystem({
diff --git a/packages/metro-bundler/src/node-haste/__tests__/Module-test.js b/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
index a31ffdff..38545b2b 100644
--- a/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
+++ b/packages/metro-bundler/src/node-haste/__tests__/Module-test.js
@@ -76,7 +76,11 @@ describe('Module', () => {
     createModule({...options, file: '/root/package.json'});
 
   beforeEach(function() {
-    process.platform = 'linux';
+    Object.defineProperty(process, 'platform', {
+      configurable: true,
+      enumerable: true,
+      value: 'linux',
+    });
     cache = createCache();
     transformCacheKey = 'abcdef';
     transformCache.mock.reset();