diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 4e52f4aac..10c264e0f 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -1160,7 +1160,7 @@ class ModelSerializer(Serializer):
         Create a read only field for model methods and properties.
         """
         field_class = ReadOnlyField
-        kwargs = {'help_text': getattr(model, field_name).__doc__}
+        field_kwargs = {'help_text': getattr(model, field_name).__doc__}
 
         return field_class, field_kwargs