diff --git a/instruments/build.js b/instruments/build.js
new file mode 100644
index 000000000..1dc828a12
--- /dev/null
+++ b/instruments/build.js
@@ -0,0 +1,25 @@
+var spawn = require('child_process').spawn;
+
+module.exports = function(appRoot, cb, sdk) {
+  if (typeof sdk == "undefined") {
+    sdk = 'iphonesimulator6.0';
+  }
+  console.log("Building app...");
+  var args = ['-sdk', sdk];
+  var xcode = spawn('xcodebuild', args, {
+    cwd: appRoot
+  });
+  var output = '';
+  var collect = function(data) { output += data; };
+  xcode.stdout.on('data', collect);
+  xcode.stderr.on('data', collect);
+  xcode.on('exit', function(code) {
+    if (code == 0) {
+      console.log("done");
+      cb(null);
+    } else {
+      console.log("Failed building app");
+      cb(output);
+    }
+  });
+};
diff --git a/instruments/example.js b/instruments/example.js
index 73167c687..6925fc193 100644
--- a/instruments/example.js
+++ b/instruments/example.js
@@ -7,37 +7,26 @@ var http = require('http')
   , ap = require('argparse').ArgumentParser
   , colors = require('colors')
   , spawn = require('child_process').spawn
+  , build = require('./build')
   , instruments = require('./instruments');
 
 app.configure(function() {
   app.use(app.router);
 });
 
-var build = function(appRoot, cb) {
-  console.log("Building app...");
-  var args = ['-sdk', 'iphonesimulator6.0'];
-  var xcode = spawn('xcodebuild', args, {
-    cwd: appRoot
-  });
-  var output = '';
-  var collect = function(data) { output += data; };
-  xcode.stdout.on('data', collect);
-  xcode.stderr.on('data', collect);
-  xcode.on('exit', function(code) {
-    if (code == 0) {
-      console.log("done");
-      cb();
-    } else {
-      console.log("Failed building app");
-      console.log(output);
-    }
-  });
-};
+app.listen(5678, 'localhost', function() {
+  console.log("Appium server running");
+});
 
 var appRoot = path.resolve(__dirname, '../sample-code/apps/TestApp/');
+var simApp = path.resolve(appRoot, 'build/Release-iphonesimulator/TestApp.app');
+
+build(appRoot, function(err) {
+  if (err) {
+    console.log(err);
+    process.exit(1);
+  }
 
-build(appRoot, function() {
-  var simApp = path.resolve(appRoot, 'build/Release-iphonesimulator/TestApp.app');
   console.log("Launching instruments...");
   var inst = instruments(
     app
@@ -57,8 +46,3 @@ build(appRoot, function() {
     process.exit(code);
   });
 });
-
-app.listen(5678, 'localhost', function() {
-  console.log("Appium server running");
-});
-