diff --git a/build/npm/postinstall.js b/build/npm/postinstall.js
new file mode 100644
index 0000000000000000000000000000000000000000..d5a065c64cdcf73e7f7e559897eff8a98edacb02
--- /dev/null
+++ b/build/npm/postinstall.js
@@ -0,0 +1,12 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+var cp = require('child_process');
+
+var extensions = ['vscode-api-tests', 'vscode-colorize-tests', 'json', 'typescript', 'php'];
+
+extensions.forEach(function (extension) {
+	cp.execSync('npm --prefix extensions/' + extension + '/ install extensions/' + extension + '/');
+});
\ No newline at end of file
diff --git a/package.json b/package.json
index c538a5e278e08f56b5da48f0f3b4c3800e59852e..9e04a536d92b3b389d6eca28d6458a8ddb921fdc 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
   "scripts": {
     "test": "mocha",
     "preinstall": "node build/npm/preinstall.js",
-    "postinstall": "npm --prefix extensions/vscode-api-tests/ install extensions/vscode-api-tests/ && npm --prefix extensions/vscode-colorize-tests/ install extensions/vscode-colorize-tests/ && npm --prefix extensions/json/ install extensions/json/ && npm --prefix extensions/typescript/ install extensions/typescript/ && npm --prefix extensions/php/ install extensions/php/",
+    "postinstall": "node build/npm/postinstall.js",
     "watch": "gulp watch"
   },
   "dependencies": {