diff --git a/rest_framework/mixins.py b/rest_framework/mixins.py
index 1104aa29c..c35834792 100644
--- a/rest_framework/mixins.py
+++ b/rest_framework/mixins.py
@@ -65,11 +65,14 @@ class UpdateModelMixin(object):
     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.update_data(request), partial=partial)
         serializer.is_valid(raise_exception=True)
         self.perform_update(serializer)
         return Response(serializer.data)
 
+    def update_data(self, request):
+        return request.data
+
     def perform_update(self, serializer):
         serializer.save()