diff --git a/rest_framework/mixins.py b/rest_framework/mixins.py
index f3695e665..55c76ee53 100644
--- a/rest_framework/mixins.py
+++ b/rest_framework/mixins.py
@@ -15,8 +15,11 @@ class CreateModelMixin(object):
     """
     Create a model instance.
     """
+    def get_request_data(self, request, *args, **kwargs):
+        return request.data
+
     def create(self, request, *args, **kwargs):
-        serializer = self.get_serializer(data=request.data)
+        serializer = self.get_serializer(data=self.get_request_data(request))
         serializer.is_valid(raise_exception=True)
         self.perform_create(serializer)
         headers = self.get_success_headers(serializer.data)
@@ -62,10 +65,13 @@ class UpdateModelMixin(object):
     """
     Update a model instance.
     """
+    def get_request_data(self, request, *args, **kwargs):
+        return request.data
+
     def update(self, request, *args, **kwargs):
         partial = kwargs.pop('partial', False)
         instance = self.get_object()
-        serializer = self.get_serializer(instance, data=request.data, partial=partial)
+        serializer = self.get_serializer(instance, data=self.get_request_data(request), partial=partial)
         serializer.is_valid(raise_exception=True)
         self.perform_update(serializer)