diff --git a/stripe/multipart_data_generator.py b/stripe/multipart_data_generator.py
index 801d3e241..9e5f03c3f 100644
--- a/stripe/multipart_data_generator.py
+++ b/stripe/multipart_data_generator.py
@@ -3,7 +3,7 @@
 import random
 import io
 
-from stripe import six
+import stripe
 
 
 class MultipartDataGenerator(object):
@@ -14,7 +14,10 @@ def __init__(self, chunk_size=1028):
         self.chunk_size = chunk_size
 
     def add_params(self, params):
-        for key, value in six.iteritems(params):
+        # Flatten parameters first
+        params = dict(stripe.api_requestor._api_encode(params))
+
+        for key, value in stripe.six.iteritems(params):
             if value is None:
                 continue
 
@@ -45,7 +48,7 @@ def add_params(self, params):
                 self._write('"')
                 self._write(self.line_break)
                 self._write(self.line_break)
-                self._write(value)
+                self._write(str(value))
 
             self._write(self.line_break)
 
@@ -58,9 +61,9 @@ def get_post_data(self):
         return self.data.getvalue()
 
     def _write(self, value):
-        if isinstance(value, six.binary_type):
+        if isinstance(value, stripe.six.binary_type):
             array = bytearray(value)
-        elif isinstance(value, six.text_type):
+        elif isinstance(value, stripe.six.text_type):
             array = bytearray(value, encoding="utf-8")
         else:
             raise TypeError(
diff --git a/tests/api_resources/test_file.py b/tests/api_resources/test_file.py
index ae2c9515c..b8e3891bd 100644
--- a/tests/api_resources/test_file.py
+++ b/tests/api_resources/test_file.py
@@ -36,7 +36,9 @@ def test_is_creatable(self, setup_upload_api_base, request_mock):
         )
         test_file = tempfile.TemporaryFile()
         resource = stripe.File.create(
-            purpose="dispute_evidence", file=test_file
+            purpose="dispute_evidence",
+            file=test_file,
+            file_link_data={"create": True},
         )
         request_mock.assert_api_base(stripe.upload_api_base)
         request_mock.assert_requested(
diff --git a/tests/api_resources/test_file_upload.py b/tests/api_resources/test_file_upload.py
index d1e72b078..faec4b5a5 100644
--- a/tests/api_resources/test_file_upload.py
+++ b/tests/api_resources/test_file_upload.py
@@ -36,7 +36,9 @@ def test_is_creatable(self, setup_upload_api_base, request_mock):
         )
         test_file = tempfile.TemporaryFile()
         resource = stripe.FileUpload.create(
-            purpose="dispute_evidence", file=test_file
+            purpose="dispute_evidence",
+            file=test_file,
+            file_link_data={"create": True},
         )
         request_mock.assert_api_base(stripe.upload_api_base)
         request_mock.assert_requested(
diff --git a/tests/test_multipart_data_generator.py b/tests/test_multipart_data_generator.py
index 07e762e98..26cf77aaf 100644
--- a/tests/test_multipart_data_generator.py
+++ b/tests/test_multipart_data_generator.py
@@ -14,6 +14,13 @@ def run_test_multipart_data_with_file(self, test_file):
             "key1": b"ASCII value",
             "key2": u"Üñìçôdé value",
             "key3": test_file,
+            "key4": {
+                "string": "Hello!",
+                "int": 234,
+                "float": 3.14159,
+                "bool": True,
+                "dict": {"foo": "bar"},
+            },
         }
         generator = MultipartDataGenerator()
         generator.add_params(params)
@@ -36,6 +43,29 @@ def run_test_multipart_data_with_file(self, test_file):
             http_body,
         )
         assert re.search(r"Content-Type: application/octet-stream", http_body)
+        assert re.search(
+            r"Content-Disposition: form-data; name=\"key4\[string\]\"",
+            http_body,
+        )
+        assert re.search(r"Hello!", http_body)
+        assert re.search(
+            r"Content-Disposition: form-data; name=\"key4\[int\]\"", http_body
+        )
+        assert re.search(r"234", http_body)
+        assert re.search(
+            r"Content-Disposition: form-data; name=\"key4\[float\]\"",
+            http_body,
+        )
+        assert re.search(r"3.14159", http_body)
+        assert re.search(
+            r"Content-Disposition: form-data; name=\"key4\[bool\]\"", http_body
+        )
+        assert re.search(r"True", http_body)
+        assert re.search(
+            r"Content-Disposition: form-data; name=\"key4\[dict\]\[foo\]\"",
+            http_body,
+        )
+        assert re.search(r"bar", http_body)
 
         test_file.seek(0)
         file_contents = test_file.read()