diff --git a/.travis.yml b/.travis.yml
index 86f95f0b90..655bbd3b4b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,8 +44,8 @@ install:
   - npm --version
   # Check the size of caches
   - du -sh ./node_modules || true
-  # Install npm dependecies and ensure that npm cache is not stale
-  - tools/npm/install-dependencies.sh
+  # Install npm dependecies
+  - npm install
 
 before_script:
 - mkdir -p $LOGS_DIR
diff --git a/gulpfile.js b/gulpfile.js
index 08461bb365..388db5a1d3 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -15,7 +15,7 @@ var madge = require('madge');
 var merge = require('merge');
 var merge2 = require('merge2');
 var path = require('path');
-var semver = require('semver');
+
 var watch = require('./tools/build/watch');
 
 var transpile = require('./tools/build/transpile');
@@ -36,6 +36,11 @@ var replace = require('gulp-replace');
 var insert = require('gulp-insert');
 var shouldLog = require('./tools/build/logging');
 
+require('./tools/check-environment')({
+  requiredNpmVersion: '>=2.9.0',
+  requiredNodeVersion: '>=0.12.2'
+});
+
 // Make it easy to quiet down portions of the build.
 // --logs=all -> log everything (This is the default)
 // --logs=quiet -> log nothing
@@ -63,35 +68,6 @@ var angularBuilder = {
   }
 };
 
-(function checkNodeAndNpmVersions() {
-  var requiredNpmVersion = '>=2.9.0';
-  var requiredNodeVersion = '>=0.12.2';
-
-  exec('npm --version', function(e, stdout) {
-    var foundNpmVersion = semver.clean(stdout);
-    var foundNodeVersion = process.version;
-    var issues = [];
-
-
-    if (!semver.satisfies(foundNodeVersion, requiredNodeVersion)) {
-      issues.push('You are running unsupported node version. Found: ' + foundNodeVersion +
-        ' Expected: ' + requiredNodeVersion);
-    }
-
-    if (!semver.satisfies(foundNpmVersion, requiredNpmVersion)) {
-      issues.push('You are running unsupported npm version. Found: ' + foundNpmVersion +
-        ' Expected: ' + requiredNpmVersion);
-    }
-
-    if (issues.length) {
-      // TODO: in the future we should error, but let's just display the warning for a few days first
-      console.warn(Array(80).join('!'));
-      console.warn('Your environment is not in a good shape. Following issues were found:');
-      issues.forEach(function(issue) {console.warn('  - ' + issue)});
-      console.warn(Array(80).join('!'));
-    }
-  });
-}());
 
 function sequenceComplete(done) {
   return function (err) {
diff --git a/package.json b/package.json
index b2b0b73047..33d5e77132 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,8 @@
     "url": "https://github.com/angular/angular.git"
   },
   "scripts": {
-    "postinstall": "node tools/chromedriverpatch.js && webdriver-manager update && bower install && gulp pubget.dart && tsd reinstall --config modules/angular2/tsd.json && tsd reinstall --config tools/tsd.json",
+    "preinstall": "node tools/npm/check-node-modules --purge",
+    "postinstall": "node tools/npm/copy-npm-shrinkwrap && node tools/chromedriverpatch.js && webdriver-manager update && bower install && gulp pubget.dart && tsd reinstall --config modules/angular2/tsd.json && tsd reinstall --config tools/tsd.json",
     "test": "gulp test.all.js && gulp test.all.dart"
   },
   "dependencies": {
diff --git a/tools/check-environment.js b/tools/check-environment.js
new file mode 100644
index 0000000000..16c473370d
--- /dev/null
+++ b/tools/check-environment.js
@@ -0,0 +1,39 @@
+var exec = require('child_process').exec;
+var semver = require('semver');
+
+var checkNodeModules = require('./npm/check-node-modules.js');
+
+
+function checkEnvironment(reqs) {
+
+  exec('npm --version', function(e, stdout) {
+    var foundNpmVersion = semver.clean(stdout);
+    var foundNodeVersion = process.version;
+    var issues = [];
+
+
+    if (!semver.satisfies(foundNodeVersion, reqs.requiredNodeVersion)) {
+      issues.push('You are running unsupported node version. Found: ' + foundNodeVersion +
+        ' Expected: ' + reqs.requiredNodeVersion + '. Use nvm to update your node version.');
+    }
+
+    if (!semver.satisfies(foundNpmVersion, reqs.requiredNpmVersion)) {
+      issues.push('You are running unsupported npm version. Found: ' + foundNpmVersion +
+        ' Expected: ' + reqs.requiredNpmVersion + '. Run: npm update -g npm');
+    }
+
+    if (!checkNodeModules()) {
+      issues.push('Your node_modules directory is stale or out of sync with npm-shrinkwrap.json. Run: npm install');
+    }
+
+    if (issues.length) {
+      console.warn(Array(80).join('!'));
+      console.warn('Your environment is not in a good shape. Following issues were found:');
+      issues.forEach(function(issue) {console.warn('  - ' + issue)});
+      console.warn(Array(80).join('!'));
+    }
+  });
+}
+
+
+module.exports = checkEnvironment;
diff --git a/tools/npm/check-node-modules b/tools/npm/check-node-modules
new file mode 100755
index 0000000000..09a1462892
--- /dev/null
+++ b/tools/npm/check-node-modules
@@ -0,0 +1,7 @@
+#!/usr/bin/env node
+
+var checkNpm = require('./check-node-modules.js');
+
+var purgeIfStale = (process.argv.indexOf('--purge') !== -1)
+
+checkNpm(true, purgeIfStale);
diff --git a/tools/npm/check-node-modules.js b/tools/npm/check-node-modules.js
new file mode 100755
index 0000000000..bd4cbd9074
--- /dev/null
+++ b/tools/npm/check-node-modules.js
@@ -0,0 +1,50 @@
+"use strict";
+
+var fs = require('fs');
+var path = require('path');
+
+var NPM_SHRINKWRAP_FILE = 'npm-shrinkwrap.json';
+var NPM_SHRINKWRAP_CACHED_FILE = 'node_modules/npm-shrinkwrap.cached.json';
+var FS_OPTS = {encoding: 'utf-8'};
+var PROJECT_ROOT = path.join(__dirname, '../../');
+
+
+function checkNodeModules(logOutput, purgeIfStale) {
+  var nodeModulesOK = _checkCache(NPM_SHRINKWRAP_FILE, NPM_SHRINKWRAP_CACHED_FILE);
+
+  if (nodeModulesOK) {
+    if (logOutput) console.log(':-) npm dependencies are looking good!');
+  } else {
+    if (logOutput) console.error(':-( npm dependencies are stale or in an in unknown state!');
+    if (purgeIfStale) {
+      if (logOutput) console.log('    purging...');
+
+      var nodeModulesPath = path.join(PROJECT_ROOT, 'node_modules');
+
+      if (fs.existsSync(nodeModulesPath)) {
+        // lazy-load fs-extra
+        var fse = require('fs-extra');
+        fse.removeSync(nodeModulesPath);
+      }
+    }
+  }
+
+  return nodeModulesOK;
+}
+
+
+function _checkCache(markerFile, cacheMarkerFile) {
+  var absoluteMarkerFilePath = path.join(PROJECT_ROOT, markerFile);
+  var absoluteCacheMarkerFilePath = path.join(PROJECT_ROOT, cacheMarkerFile);
+
+
+  if (!fs.existsSync(absoluteCacheMarkerFilePath)) return false;
+
+  var markerContent = fs.readFileSync(absoluteMarkerFilePath, FS_OPTS);
+  var cacheMarkerContent = fs.readFileSync(absoluteCacheMarkerFilePath, FS_OPTS);
+
+  return markerContent == cacheMarkerContent;
+}
+
+
+module.exports = checkNodeModules;
diff --git a/tools/npm/copy-npm-shrinkwrap b/tools/npm/copy-npm-shrinkwrap
new file mode 100755
index 0000000000..ad1fea788e
--- /dev/null
+++ b/tools/npm/copy-npm-shrinkwrap
@@ -0,0 +1,12 @@
+#!/usr/bin/env node
+
+var fse = require('fs-extra');
+var path = require('path');
+
+var NPM_SHRINKWRAP_FILE = 'npm-shrinkwrap.json';
+var NPM_SHRINKWRAP_CACHED_FILE = 'node_modules/npm-shrinkwrap.cached.json';
+var PROJECT_ROOT = path.join(__dirname, '../../');
+
+process.chdir(PROJECT_ROOT);
+
+fse.copySync(NPM_SHRINKWRAP_FILE, NPM_SHRINKWRAP_CACHED_FILE);
diff --git a/tools/npm/install-dependencies.sh b/tools/npm/install-dependencies.sh
deleted file mode 100755
index b4a828a00b..0000000000
--- a/tools/npm/install-dependencies.sh
+++ /dev/null
@@ -1,18 +0,0 @@
-#!/bin/bash
-
-set -e
-
-SHRINKWRAP_FILE=npm-shrinkwrap.json
-SHRINKWRAP_CACHED_FILE=node_modules/npm-shrinkwrap.cached.json
-
-if diff -q $SHRINKWRAP_FILE $SHRINKWRAP_CACHED_FILE; then
-  echo 'No shrinkwrap changes detected. npm install will be skipped...';
-  echo 'Running npm postinstall'
-  npm run postinstall
-else
-  echo 'Blowing away node_modules and reinstalling npm dependencies...'
-  rm -rf node_modules
-  npm install
-  cp $SHRINKWRAP_FILE $SHRINKWRAP_CACHED_FILE
-  echo 'npm install successful!'
-fi