diff --git a/moto/core/models.py b/moto/core/models.py
index 73942c669..460823bd6 100644
--- a/moto/core/models.py
+++ b/moto/core/models.py
@@ -12,6 +12,8 @@ from io import BytesIO
 from collections import defaultdict
 from botocore.handlers import BUILTIN_HANDLERS
 from botocore.awsrequest import AWSResponse
+from six.moves.urllib.parse import urlparse
+from werkzeug.wrappers import Request
 
 import mock
 from moto import settings
@@ -175,6 +177,24 @@ class CallbackResponse(responses.CallbackResponse):
         """
         Need to override this so we can pass decode_content=False
         """
+        if not isinstance(request, Request):
+            url = urlparse(request.url)
+            if request.body is None:
+                body = None
+            elif isinstance(request.body, six.text_type):
+                body = six.BytesIO(six.b(request.body))
+            else:
+                body = six.BytesIO(request.body)
+            req = Request.from_values(
+                path='?'.join([url.path, url.query]),
+                input_stream=body,
+                content_length=request.headers.get("Content-Length"),
+                content_type=request.headers.get("Content-Type"),
+                method=request.method,
+                base_url='{scheme}://{netloc}'.format(scheme=url.scheme, netloc=url.netloc),
+                headers=[(k, v) for k, v in six.iteritems(request.headers)]
+            )
+            request = req
         headers = self.get_headers()
 
         result = self.callback(request)
diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 6ac139a14..442489a8a 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -5,7 +5,6 @@ import sys
 
 import six
 from botocore.awsrequest import AWSPreparedRequest
-from werkzeug.wrappers import Request
 
 from moto.core.utils import str_to_rfc_1123_datetime, py2_strip_unicode_keys
 from six.moves.urllib.parse import parse_qs, urlparse, unquote, parse_qsl
@@ -797,14 +796,6 @@ class ResponseObject(_TemplateEnvironmentMixin, ActionAuthenticatorMixin):
         if hasattr(request, "form"):
             # Not HTTPretty
             form = request.form
-        elif request.headers.get("Content-Type").startswith("multipart/form-data"):
-            request = Request.from_values(
-                input_stream=six.BytesIO(request.body),
-                content_length=request.headers["Content-Length"],
-                content_type=request.headers["Content-Type"],
-                method="POST",
-            )
-            form = request.form
         else:
             # HTTPretty, build new form object
             body = body.decode()