diff --git a/README.md b/README.md
index 70cc1310..01f37499 100644
--- a/README.md
+++ b/README.md
@@ -99,6 +99,24 @@ If you don't have the full server environment running, you can launch a one-off
 1. `$ npm install -g pm2`
 2. `$ pm2 start ecosystem.json`
 
+## Optional S3 bucket URL base configuration
+
+If your S3 bucket is in the US East (N Virginia) region (us-east-1), you'll
+need to set a custom URL base for it, because it does not follow the standard
+naming pattern as the rest of the regions. Instead, add the following to your
+environment/.env file:
+
+```S3_BUCKET_URL_BASE=https://s3.amazonaws.com```
+
+If you've configured your S3 bucket and DNS records to use a custom domain
+name, you can also set it using this variable. I.e.:
+
+```S3_BUCKET_URL_BASE=https://files.mydomain.com```
+
+For more information on using a custom domain, see this documentation link:
+
+http://docs.aws.amazon.com/AmazonS3/latest/dev/VirtualHosting.html#VirtualHostingCustomURLs
+
 ## Accessibility Guidelines
 
 Here is guide on [how to use the accessible editor](https://gist.github.com/MathuraMG/e86666b7b41fbc8c078bad9aff3f666d)
diff --git a/client/modules/IDE/actions/uploader.js b/client/modules/IDE/actions/uploader.js
index 223a38bd..1ec2208b 100644
--- a/client/modules/IDE/actions/uploader.js
+++ b/client/modules/IDE/actions/uploader.js
@@ -2,7 +2,8 @@ import axios from 'axios';
 import { createFile } from './files';
 
 const textFileRegex = /(text\/|application\/json)/;
-const s3BucketHttps = `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
+const s3BucketHttps = process.env.S3_BUCKET_URL_BASE ||
+                      `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
 const ROOT_URL = process.env.API_URL;
 const MAX_LOCAL_FILE_SIZE = 80000; // bytes, aka 80 KB
 
diff --git a/client/modules/IDE/components/FileUploader.jsx b/client/modules/IDE/components/FileUploader.jsx
index 0b523efd..9c109764 100644
--- a/client/modules/IDE/components/FileUploader.jsx
+++ b/client/modules/IDE/components/FileUploader.jsx
@@ -4,7 +4,8 @@ import { bindActionCreators } from 'redux';
 import { connect } from 'react-redux';
 import * as UploaderActions from '../actions/uploader';
 
-const s3Bucket = `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
+const s3Bucket = process.env.S3_BUCKET_URL_BASE ||
+                 `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
 
 class FileUploader extends React.Component {
   componentDidMount() {
diff --git a/index.js b/index.js
index 6d5ed22e..ae64c308 100644
--- a/index.js
+++ b/index.js
@@ -4,5 +4,11 @@ if (process.env.NODE_ENV === 'production') {
 }
 require('babel-register');
 require('babel-polyfill');
-require('dotenv').config();
-require('./server/server');
\ No newline at end of file
+let parsed = require('dotenv').config();
+//// in development, let .env values override those in the environment already (i.e. in docker-compose.yml)
+if (process.env.NODE_ENV === 'development') {
+  for (let key in parsed) {
+    process.env[key] = parsed[key];
+  }
+}
+require('./server/server');
diff --git a/server/controllers/aws.controller.js b/server/controllers/aws.controller.js
index 2faf8938..a5e507e8 100644
--- a/server/controllers/aws.controller.js
+++ b/server/controllers/aws.controller.js
@@ -17,7 +17,8 @@ const client = s3.createClient({
   },
 });
 
-const s3Bucket = `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
+const s3Bucket = process.env.S3_BUCKET_URL_BASE ||
+                 `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/`;
 
 function getExtension(filename) {
   const i = filename.lastIndexOf('.');
diff --git a/server/migrations/s3UnderUser.js b/server/migrations/s3UnderUser.js
index 289d212e..d22317c5 100644
--- a/server/migrations/s3UnderUser.js
+++ b/server/migrations/s3UnderUser.js
@@ -15,8 +15,8 @@ let client = s3.createClient({
   maxAsyncS3: 20,
   s3RetryCount: 3,
   s3RetryDelay: 1000,
-  multipartUploadThreshold: 20971520, // this is the default (20 MB) 
-  multipartUploadSize: 15728640, // this is the default (15 MB) 
+  multipartUploadThreshold: 20971520, // this is the default (20 MB)
+  multipartUploadSize: 15728640, // this is the default (15 MB)
   s3Options: {
     accessKeyId: `${process.env.AWS_ACCESS_KEY}`,
     secretAccessKey: `${process.env.AWS_SECRET_KEY}`,
@@ -43,7 +43,8 @@ Project.find({}, (err, projects) => {
             console.log(err);
           })
           .on('end', () => {
-            file.url = `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}/${userId}/${key}`;
+            file.url = (process.env.S3_BUCKET_URL_BASE ||
+                        `https://s3-${process.env.AWS_REGION}.amazonaws.com/${process.env.S3_BUCKET}`) + `/${userId}/${key}`;
             project.save((err, savedProject) => {
               console.log(`updated file ${key}`);
             });
@@ -54,4 +55,4 @@ Project.find({}, (err, projects) => {
       }
     });
   });
-});
\ No newline at end of file
+});
diff --git a/webpack.config.dev.js b/webpack.config.dev.js
index 42d6cadf..67127f20 100644
--- a/webpack.config.dev.js
+++ b/webpack.config.dev.js
@@ -41,6 +41,7 @@ module.exports = {
           JSON.stringify(false),
         'NODE_ENV': JSON.stringify('development'),
         'S3_BUCKET': '"' + process.env.S3_BUCKET + '"',
+        'S3_BUCKET_URL_BASE': '"' + process.env.S3_BUCKET_URL_BASE + '"',
         'AWS_REGION': '"' + process.env.AWS_REGION + '"',
       }
     })
diff --git a/webpack.config.prod.js b/webpack.config.prod.js
index a860d5c2..e5f9d037 100644
--- a/webpack.config.prod.js
+++ b/webpack.config.prod.js
@@ -82,6 +82,7 @@ module.exports = {
         'API_URL': '"' + process.env.API_URL + '"',
         'NODE_ENV': JSON.stringify('production'),
         'S3_BUCKET': '"' + process.env.S3_BUCKET + '"',
+        'S3_BUCKET_URL_BASE': '"' + process.env.S3_BUCKET_URL_BASE + '"',
         'AWS_REGION': '"' + process.env.AWS_REGION + '"'
       }
     }),