diff --git a/rest_framework/mixins.py b/rest_framework/mixins.py
index 93b5bd684..bf2b60b5f 100644
--- a/rest_framework/mixins.py
+++ b/rest_framework/mixins.py
@@ -14,7 +14,8 @@ class CreateModelMixin:
     Create a model instance.
     """
     def create(self, request, *args, **kwargs):
-        serializer = self.get_serializer(data=self.get_create_data(request))
+        data = self.get_create_data(request)
+        serializer = self.get_serializer(data=data)
         serializer.is_valid(raise_exception=True)
         self.perform_create(serializer)
         headers = self.get_success_headers(serializer.data)
@@ -66,7 +67,8 @@ class UpdateModelMixin:
     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)
+        data = self.get_update_data(request)
+        serializer = self.get_serializer(instance, data=data, partial=partial)
         serializer.is_valid(raise_exception=True)
         self.perform_update(serializer)
 
@@ -77,6 +79,9 @@ class UpdateModelMixin:
 
         return Response(serializer.data)
 
+    def get_update_data(self, request):
+        return request.data
+
     def perform_update(self, serializer):
         serializer.save()