diff --git a/lib/MultipartDataGenerator.js b/lib/MultipartDataGenerator.js
index 321820ad73..4225375c40 100644
--- a/lib/MultipartDataGenerator.js
+++ b/lib/MultipartDataGenerator.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var Buffer = require('safe-buffer').Buffer;
+var utils = require('./utils');
 
 // Method for formatting HTTP body for the multipart/form-data specification
 // Mostly taken from Fermata.js
@@ -23,7 +24,7 @@ function multipartDataGenerator(method, data, headers) {
     return '"' + s.replace(/"|"/g, '%22').replace(/\r\n|\r|\n/g, ' ') + '"';
   }
 
-  for (var k in data) {
+  for (var k in utils.flattenAndStringify(data)) {
     var v = data[k];
     push('--' + segno);
     if (v.hasOwnProperty('data')) {
diff --git a/lib/utils.js b/lib/utils.js
index 44b378a755..d74ea0f432 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -250,6 +250,41 @@ var utils = module.exports = {
 
   // For mocking in tests.
   _exec: exec,
+
+  isObject: function isObject(obj) {
+    var type = typeof obj;
+    return (type === 'function' || type === 'object') && !!obj;
+  },
+
+  // For use in multipart requests
+  flattenAndStringify: function flattenAndStringify(data) {
+    var result = {};
+
+    function step(obj, prevKey) {
+      Object.keys(obj).forEach(function (key) {
+        var value = obj[key];
+
+        var newKey = prevKey ? `${prevKey}[${key}]` : key;
+
+        if (utils.isObject(value)) {
+          if (!Buffer.isBuffer(value) && !value.hasOwnProperty('data')) {
+            // Non-buffer non-file Objects are recursively flattened
+            return step(value, newKey);
+          } else {
+            // Buffers and file objects are stored without modification
+            result[newKey] = value;
+          }
+        } else {
+          // Primitives are converted to strings
+          result[newKey] = String(value);
+        }
+      })
+    }
+
+    step(data);
+
+    return result;
+  },
 };
 
 function emitWarning(warning) {
diff --git a/test/resources/FileUploads.spec.js b/test/resources/FileUploads.spec.js
index cf839ca5ee..c8ea6bb6dd 100644
--- a/test/resources/FileUploads.spec.js
+++ b/test/resources/FileUploads.spec.js
@@ -55,6 +55,7 @@ describe('File Uploads Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       });
 
       expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
@@ -73,6 +74,7 @@ describe('File Uploads Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }, TEST_AUTH_KEY);
 
       expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
@@ -92,6 +94,7 @@ describe('File Uploads Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }).then(function() {
         expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
         expect(stripe.LAST_REQUEST).to.deep.property('method', 'POST');
@@ -110,6 +113,7 @@ describe('File Uploads Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }, TEST_AUTH_KEY).then(function() {
         expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
         expect(stripe.LAST_REQUEST).to.deep.property('method', 'POST');
diff --git a/test/resources/Files.spec.js b/test/resources/Files.spec.js
index 01affd912e..215652cec1 100644
--- a/test/resources/Files.spec.js
+++ b/test/resources/Files.spec.js
@@ -55,6 +55,7 @@ describe('Files Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       });
 
       expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
@@ -73,6 +74,7 @@ describe('Files Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }, TEST_AUTH_KEY);
 
       expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
@@ -92,6 +94,7 @@ describe('Files Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }).then(function() {
         expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
         expect(stripe.LAST_REQUEST).to.deep.property('method', 'POST');
@@ -110,6 +113,7 @@ describe('Files Resource', function() {
           name: 'minimal.pdf',
           type: 'application/octet-stream',
         },
+        file_link_data: {create: true},
       }, TEST_AUTH_KEY).then(function() {
         expect(stripe.LAST_REQUEST).to.deep.property('host', 'files.stripe.com');
         expect(stripe.LAST_REQUEST).to.deep.property('method', 'POST');
diff --git a/test/utils.spec.js b/test/utils.spec.js
index 601c39a6a5..f406535825 100644
--- a/test/utils.spec.js
+++ b/test/utils.spec.js
@@ -4,6 +4,7 @@ require('../testUtils');
 
 var utils = require('../lib/utils');
 var expect = require('chai').expect;
+var Buffer = require('safe-buffer').Buffer;
 
 describe('utils', function() {
   describe('makeURLInterpolator', function() {
@@ -338,6 +339,51 @@ describe('utils', function() {
       ]);
     });
   })
+
+  describe('flattenAndStringify', function() {
+    it('Stringifies primitive types', function() {
+      expect(utils.flattenAndStringify({
+        a: 1,
+        b: 'foo',
+        c: true,
+        d: null,
+      })).to.eql({'a': '1', 'b': 'foo', 'c': 'true', 'd': 'null'});
+    });
+
+    it('Flattens nested values', function() {
+      expect(utils.flattenAndStringify({
+        x: {
+          a: 1,
+          b: 'foo',
+        },
+      })).to.eql({'x[a]': '1', 'x[b]': 'foo'});
+    });
+
+    it('Does not flatten File objects', function() {
+      expect(utils.flattenAndStringify({
+        file: {
+          data: 'foo'
+        },
+        x: {
+          a: 1,
+        },
+      })).to.eql({'file': {data: 'foo'}, 'x[a]': '1'});
+    });
+
+    it('Does not flatten Buffer objects', function() {
+      var buf = Buffer.from('Hi!');
+      var flattened = utils.flattenAndStringify({
+        buf: buf,
+        x: {
+          a: 1,
+        },
+      });
+      expect(flattened).to.have.property('buf');
+      expect(flattened.buf).to.deep.equal(buf);
+      expect(flattened).to.have.property('x[a]');
+      expect(flattened['x[a]']).to.equal('1');
+    });
+  });
 });
 
 function handleWarnings(doWithShimmedConsoleWarn, onWarn) {