diff --git a/jakelib/fetch.jake b/jakelib/fetch.jake
index 7cb607f..37ca43f 100644
--- a/jakelib/fetch.jake
+++ b/jakelib/fetch.jake
@@ -1,5 +1,6 @@
 'use strict';
 
+var crypto = require('crypto');
 var download = require('download');
 var fs = require('fs');
 var getPackageName = require('./common').getPackageName;
@@ -10,28 +11,50 @@ var WebRTCUrl = pkg.config.webrtc.url;
 var WebRTCRev = pkg.config.webrtc.revision;
 var ChromiumUrl = pkg.config.chromium.url;
 
+function checksum(bytes) {
+  return crypto
+    .createHash('md5')
+    .update(bytes, 'utf8')
+    .digest('hex')
+}
+
 namespace('fetch', function () {
-  task('precompiled', {async: true}, function () {
-    var packageName = getPackageName();
-    var url = pkg.config.url + '/' + pkg.version + '/' + packageName;
+  task('precompiled', ['check-file'], function () {
+  });
+
+  task('check-file', function () {
+    try {
+      var data = fs.readFileSync(getPackageName());
+
+      if (checksum(data) !== pkg.config.webrtc.checksum) {
+        throw new Error('Invalid checksum');
+      }
+
+      jake.Task['fetch:extract'].invoke();
+    } catch (e) {
+      jake.Task['fetch:download'].invoke();
+    }
+  });
+
+  task('download', {async: true}, function () {
+    var url = pkg.config.url + '/' + pkg.version + '/' + getPackageName();
 
     console.log('Downloading', url);
     download(url, '.')
       .then(function () {
-        console.log('Extracting', packageName);
-        jake.exec('tar xf ' + packageName, function () {
-          console.log('Deleting', packageName);
-          fs.unlinkSync(packageName);
-          console.log('Done');
+        var task = jake.Task['fetch:extract'];
+
+        task.addListener('complete', function () {
           complete();
         });
+
+        task.invoke();
       })
       .catch(function (err) {
         var task = jake.Task['fetch:source'];
 
         console.log('Failed, building libwebrtc from source.');
         task.addListener('complete', function () {
-          console.log('Build done.');
           complete();
         });
 
@@ -39,6 +62,17 @@ namespace('fetch', function () {
       });
   });
 
+  task('extract', {async: true}, function () {
+    var packageName = getPackageName();
+
+    console.log('Extracting', packageName);
+    jake.exec('tar xf ' + packageName, function () {
+      console.log('Deleting', packageName);
+      fs.unlinkSync(packageName);
+      complete();
+    });
+  });
+
   task('gclient', {async: true}, function () {
     console.log('Updating submodules...');
     jake.exec(['git submodule init', 'git submodule update'], {printStdout: true}, function () {
diff --git a/package.json b/package.json
index 890d9f8..fa39afa 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,8 @@
     "url": "https://github.com/aisouard/libwebrtc/releases/download",
     "webrtc": {
       "url": "https://chromium.googlesource.com/external/webrtc.git",
-      "revision": "7502401788fcba5c9f81a9e4701e2f0831e78698"
+      "revision": "7502401788fcba5c9f81a9e4701e2f0831e78698",
+      "checksum": "9fc7a9b4c576278a328c276cfb233459"
     },
     "chromium": {
       "url": "https://github.com/aisouard/libwebrtc-chromium-deps.git"