diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 7ca2d57ab..6b3e3a3a4 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -1080,6 +1080,7 @@ class ModelSerializer(Serializer):
                         extra_field_kwargs=extra_field_kwargs
                     )
                 )
+                fields[field_name] = declared_fields[field_name]
                 continue
 
             source = extra_field_kwargs.get('source', '*')