diff --git a/dist/crc16.js b/dist/crc16.js
index 017627d..7be2075 100644
--- a/dist/crc16.js
+++ b/dist/crc16.js
@@ -27,7 +27,6 @@
 
  // https://github.com/umdjs/umd
 (function(global, factory) {
-
     if (typeof exports === 'object') {
         // CommonJS (Node)
         module.exports = factory();
@@ -38,7 +37,6 @@
         // Browser global (with support for web workers)
         global.crc16 = factory();
     }
-
 }(this, function() {
     'use strict';
 
diff --git a/dist/dfu.js b/dist/dfu.js
index fd554b9..de90066 100644
--- a/dist/dfu.js
+++ b/dist/dfu.js
@@ -33,15 +33,15 @@
 (function (root, factory) {
     if (typeof define === 'function' && define.amd) {
         // AMD. Register as an anonymous module.
-        define(['es6-promise', 'bleat'], factory);
+        define(['es6-promise', 'bleat', 'crc16'], factory);
     } else if (typeof exports === 'object') {
         // Node. Does not work with strict CommonJS
-        module.exports = factory(Promise, require('bleat').webbluetooth);
+        module.exports = factory(Promise, require('bleat').webbluetooth, require('./crc16'));
     } else {
         // Browser globals with support for web workers (root is window)
-        root.dfu = factory(Promise, root.navigator.bluetooth);
+        root.dfu = factory(Promise, root.navigator.bluetooth, root.crc16);
     }
-}(this, function(Promise, bluetooth) {
+}(this, function(Promise, bluetooth, crc16) {
     "use strict";
 
     var LITTLE_ENDIAN = true;
@@ -162,16 +162,17 @@
         return view;
     }
 
-    function provision(device, arrayBuffer, crc, imageType) {
+    function provision(device, arrayBuffer, imageType, crc) {
         return new Promise(function(resolve, reject) {
-            var versionChar = null;
-            initPacket.crc = crc || 0xFFFF; // Not used in mbed/ older bootloader revisions.
             imageType = imageType || ImageType.Application;
+            initPacket.crc = crc || crc16(arrayBuffer);
+            var versionChar = null;
 
             connect(device)
             .then(function(chars) {
                 versionChar = chars.versionChar;
-                if (versionChar) { // Older DFU implementations (from older Nordic SDKs < 7.0) have no DFU Version characteristic.
+                // Older DFU implementations (from older Nordic SDKs < 7.0) have no DFU Version characteristic.
+                if (versionChar) {
                     return versionChar.readValue()
                     .then(function(data) {
                         console.log('read versionChar');
diff --git a/dist/hex2bin.js b/dist/hex2bin.js
index d17728b..9065db8 100644
--- a/dist/hex2bin.js
+++ b/dist/hex2bin.js
@@ -27,7 +27,6 @@
 
  // https://github.com/umdjs/umd
 (function(global, factory) {
-
     if (typeof exports === 'object') {
         // CommonJS (Node)
         module.exports = factory();
@@ -38,7 +37,6 @@
         // Browser global (with support for web workers)
         global.hex2bin = factory();
     }
-
 }(this, function() {
     'use strict';
 
diff --git a/example_node.js b/example_node.js
index 8568252..7bc7f72 100644
--- a/example_node.js
+++ b/example_node.js
@@ -1,6 +1,5 @@
 var dfu = require('./index').dfu;
 var hex2bin = require('./index').hex2bin;
-var crc16 = require('./index').crc16;
 var fs = require('fs');
 
 var log = console.log;
@@ -41,9 +40,8 @@ dfu.findDevice({ services: [0x180D] })
     var hex = file.toString();
     var buffer = hex2bin(hex);
     log("file length: " + buffer.byteLength);
-    var crc = crc16(buffer);
 
-    return dfu.provision(device, buffer, crc);
+    return dfu.provision(device, buffer);
 })
 .then(() => process.exit())
 .catch(error => {
diff --git a/example_web.html b/example_web.html
index d5a82fd..8299a17 100644
--- a/example_web.html
+++ b/example_web.html
@@ -27,7 +27,6 @@
 
     <script src="dist/dfu.js"></script>
     <script src="dist/hex2bin.js"></script>
-    <script src="dist/crc16.js"></script>
 
     <script>
         var resultsEl = document.getElementById("results");
@@ -69,9 +68,10 @@
                 .then(hex => {
                     var buffer = hex2bin(hex);
                     log("downloaded length: " + buffer.byteLength);
-                    var crc = crc16(buffer);
 
-                    return dfu.provision(device, buffer, crc); // dfu.ImageType.Application is the default value for the fourth parameter. Specify this if you want to upload a softdevice/bootloader.
+                    // dfu.ImageType.Application is the default value for the third parameter
+                    // Specify this if you want to upload a softdevice/bootloader
+                    return dfu.provision(device, buffer);
                 })
                 .then(() => {
                     log('dfu complete');