diff --git a/package-lock.json b/package-lock.json
index 17a11ba..2904e22 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "c3",
-  "version": "0.4.13",
+  "version": "0.4.14",
   "lockfileVersion": 1,
   "dependencies": {
     "abbrev": {
@@ -297,6 +297,12 @@
       "integrity": "sha1-NRV7EBQm/S/9PaP3XH0ekYNbv4o=",
       "dev": true
     },
+    "babel-plugin-external-helpers": {
+      "version": "6.22.0",
+      "resolved": "https://registry.npmjs.org/babel-plugin-external-helpers/-/babel-plugin-external-helpers-6.22.0.tgz",
+      "integrity": "sha1-IoX0iwK9Xe3oUXXK+MYuhq3M76E=",
+      "dev": true
+    },
     "babel-plugin-istanbul": {
       "version": "4.1.4",
       "resolved": "https://registry.npmjs.org/babel-plugin-istanbul/-/babel-plugin-istanbul-4.1.4.tgz",
@@ -1292,6 +1298,12 @@
       "integrity": "sha1-/cpRzuYTOJXjyI1TXOSdv/YqRjM=",
       "dev": true
     },
+    "estree-walker": {
+      "version": "0.2.1",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-0.2.1.tgz",
+      "integrity": "sha1-va/oCVOD2EFNXcLs9MkXO225QS4=",
+      "dev": true
+    },
     "esutils": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/esutils/-/esutils-2.0.2.tgz",
@@ -3680,6 +3692,18 @@
       "integrity": "sha1-4NBUl4d6OYwQTYFtJzOnGKepTio=",
       "dev": true
     },
+    "rollup-plugin-babel": {
+      "version": "2.7.1",
+      "resolved": "https://registry.npmjs.org/rollup-plugin-babel/-/rollup-plugin-babel-2.7.1.tgz",
+      "integrity": "sha1-FlKBl7D5OKFTb0RoPHqT1XMYL1c=",
+      "dev": true
+    },
+    "rollup-pluginutils": {
+      "version": "1.5.2",
+      "resolved": "https://registry.npmjs.org/rollup-pluginutils/-/rollup-pluginutils-1.5.2.tgz",
+      "integrity": "sha1-HhVud4+UtyVb+hs9AXi+j1xVJAg=",
+      "dev": true
+    },
     "safe-buffer": {
       "version": "5.0.1",
       "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.0.1.tgz",
diff --git a/package.json b/package.json
index 44d4cb8..81e08d9 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
     "lint": "jshint --reporter=node_modules/jshint-stylish src/ spec/",
     "build": "npm run build:js && npm run build:css",
     "build:js": "npm run build:js:rollup && npm run build:js:uglify",
-    "build:js:rollup": "rollup -f umd --name c3 --globals d3:d3 src/index.js > c3.js",
+    "build:js:rollup": "rollup -c > c3.js",
     "build:js:uglify": "uglifyjs c3.js --compress --mangle -o c3.min.js",
     "build:css": "npm run build:css:sass && npm run build:css:min",
     "build:css:sass": "node-sass src/scss/main.scss > c3.css",
@@ -38,6 +38,7 @@
     "d3": "~3.5.0"
   },
   "devDependencies": {
+    "babel-plugin-external-helpers": "^6.22.0",
     "babel-plugin-istanbul": "^4.1.4",
     "babel-preset-es2015": "^6.24.1",
     "babelify": "^7.3.0",
@@ -56,6 +57,7 @@
     "node-sass": "^4.5.3",
     "node-static": "^0.7.9",
     "rollup": "^0.41.6",
+    "rollup-plugin-babel": "^2.7.1",
     "uglify-js": "^3.0.15",
     "watchify": "^3.9.0"
   },
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 0000000..7f14b76
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,15 @@
+import babel from 'rollup-plugin-babel';
+
+export default {
+    entry: 'src/index.js',
+    format: 'umd',
+    moduleName: 'c3',
+    plugins: [babel({
+        presets: [['es2015', {
+            modules: false
+        }]],
+        plugins: [
+            'external-helpers'
+        ]
+    })]
+};
diff --git a/src/api.flow.js b/src/api.flow.js
index a9431aa..3c3a660 100644
--- a/src/api.flow.js
+++ b/src/api.flow.js
@@ -1,6 +1,7 @@
 import CLASS from './class';
 import { c3_chart_fn, c3_chart_internal_fn } from './core';
 import { isValue, isDefined, diffDomain } from './util';
+import { convertRowsToData, convertColumnsToData } from './data.convert.utils';
 
 c3_chart_fn.flow = function (args) {
     var $$ = this.internal,
@@ -11,10 +12,10 @@ c3_chart_fn.flow = function (args) {
         data = $$.convertJsonToData(args.json, args.keys);
     }
     else if (args.rows) {
-        data = $$.convertRowsToData(args.rows);
+        data = convertRowsToData(args.rows);
     }
     else if (args.columns) {
-        data = $$.convertColumnsToData(args.columns);
+        data = convertColumnsToData(args.columns);
     }
     else {
         return;
diff --git a/src/core.js b/src/core.js
index fc2676b..f5977f1 100644
--- a/src/core.js
+++ b/src/core.js
@@ -1,6 +1,7 @@
 import Axis from './axis';
 import CLASS from './class';
 import { isValue, isFunction, isString, isUndefined, isDefined, ceil10, asHalfPixel, diffDomain, isEmpty, notEmpty, getOption, hasValue, sanitise, getPathBox } from './util';
+import { convertRowsToData, convertColumnsToData } from './data.convert.utils';
 
 export var c3 = { version: "0.4.14" };
 
@@ -91,10 +92,10 @@ c3_chart_internal_fn.init = function () {
         $$.initWithData($$.convertJsonToData(config.data_json, config.data_keys));
     }
     else if (config.data_rows) {
-        $$.initWithData($$.convertRowsToData(config.data_rows));
+        $$.initWithData(convertRowsToData(config.data_rows));
     }
     else if (config.data_columns) {
-        $$.initWithData($$.convertColumnsToData(config.data_columns));
+        $$.initWithData(convertColumnsToData(config.data_columns));
     }
     else {
         throw Error('url or json or rows or columns is required.');
diff --git a/src/data.convert.js b/src/data.convert.js
index 34808a9..a7da7d1 100644
--- a/src/data.convert.js
+++ b/src/data.convert.js
@@ -1,5 +1,6 @@
 import { c3_chart_internal_fn } from './core';
 import { isValue, isUndefined, isDefined, notEmpty } from './util';
+import { convertRowsToData, convertColumnsToData } from './data.convert.utils';
 
 c3_chart_internal_fn.convertUrlToData = function (url, mimeType, headers, keys, done) {
     var $$ = this, type = mimeType ? mimeType : 'csv';
@@ -66,12 +67,12 @@ c3_chart_internal_fn.convertJsonToData = function (json, keys) {
             });
             new_rows.push(new_row);
         });
-        data = $$.convertRowsToData(new_rows);
+        data = convertRowsToData(new_rows);
     } else {
         Object.keys(json).forEach(function (key) {
             new_rows.push([key].concat(json[key]));
         });
-        data = $$.convertColumnsToData(new_rows);
+        data = convertColumnsToData(new_rows);
     }
     return data;
 };
@@ -89,36 +90,7 @@ c3_chart_internal_fn.findValueInJson = function (object, path) {
     }
     return object;
 };
-c3_chart_internal_fn.convertRowsToData = function (rows) {
-    var keys = rows[0], new_row = {}, new_rows = [], i, j;
-    for (i = 1; i < rows.length; i++) {
-        new_row = {};
-        for (j = 0; j < rows[i].length; j++) {
-            if (isUndefined(rows[i][j])) {
-                throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
-            }
-            new_row[keys[j]] = rows[i][j];
-        }
-        new_rows.push(new_row);
-    }
-    return new_rows;
-};
-c3_chart_internal_fn.convertColumnsToData = function (columns) {
-    var new_rows = [], i, j, key;
-    for (i = 0; i < columns.length; i++) {
-        key = columns[i][0];
-        for (j = 1; j < columns[i].length; j++) {
-            if (isUndefined(new_rows[j - 1])) {
-                new_rows[j - 1] = {};
-            }
-            if (isUndefined(columns[i][j])) {
-                throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
-            }
-            new_rows[j - 1][key] = columns[i][j];
-        }
-    }
-    return new_rows;
-};
+
 c3_chart_internal_fn.convertDataToTargets = function (data, appendXs) {
     var $$ = this, config = $$.config,
         ids = $$.d3.keys(data[0]).filter($$.isNotX, $$),
diff --git a/src/data.convert.utils.js b/src/data.convert.utils.js
new file mode 100644
index 0000000..55b146d
--- /dev/null
+++ b/src/data.convert.utils.js
@@ -0,0 +1,49 @@
+import { isUndefined } from './util';
+
+/**
+ * Converts the rows to data.
+ * @param {any[][]} rows The row data
+ * @return {any[][]}
+ */
+export const convertRowsToData = (rows) => {
+    const new_rows = [];
+    const keys = rows[0];
+    let new_row , i, j;
+
+    for (i = 1; i < rows.length; i++) {
+        new_row = {};
+        for (j = 0; j < rows[i].length; j++) {
+            if (isUndefined(rows[i][j])) {
+                throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
+            }
+            new_row[keys[j]] = rows[i][j];
+        }
+        new_rows.push(new_row);
+    }
+    return new_rows;
+};
+
+/**
+ * Converts the columns to data.
+ * @param {any[][]} columns The column data
+ * @return {any[][]}
+ */
+export const convertColumnsToData = (columns) => {
+    const new_rows = [];
+    let i, j, key;
+
+    for (i = 0; i < columns.length; i++) {
+        key = columns[i][0];
+        for (j = 1; j < columns[i].length; j++) {
+            if (isUndefined(new_rows[j - 1])) {
+                new_rows[j - 1] = {};
+            }
+            if (isUndefined(columns[i][j])) {
+                throw new Error("Source data is missing a component at (" + i + "," + j + ")!");
+            }
+            new_rows[j - 1][key] = columns[i][j];
+        }
+    }
+
+    return new_rows;
+};
diff --git a/src/data.load.js b/src/data.load.js
index 376d7e9..12da7b2 100644
--- a/src/data.load.js
+++ b/src/data.load.js
@@ -1,5 +1,6 @@
 import CLASS from './class';
 import { c3_chart_internal_fn } from './core';
+import { convertRowsToData, convertColumnsToData } from './data.convert.utils';
 
 c3_chart_internal_fn.load = function (targets, args) {
     var $$ = this;
@@ -50,10 +51,10 @@ c3_chart_internal_fn.loadFromArgs = function (args) {
         $$.load($$.convertDataToTargets($$.convertJsonToData(args.json, args.keys)), args);
     }
     else if (args.rows) {
-        $$.load($$.convertDataToTargets($$.convertRowsToData(args.rows)), args);
+        $$.load($$.convertDataToTargets(convertRowsToData(args.rows)), args);
     }
     else if (args.columns) {
-        $$.load($$.convertDataToTargets($$.convertColumnsToData(args.columns)), args);
+        $$.load($$.convertDataToTargets(convertColumnsToData(args.columns)), args);
     }
     else {
         $$.load(null, args);