diff --git a/rest_framework/utils/field_mapping.py b/rest_framework/utils/field_mapping.py
index 50de3f125..483d8375f 100644
--- a/rest_framework/utils/field_mapping.py
+++ b/rest_framework/utils/field_mapping.py
@@ -100,7 +100,8 @@ def get_field_kwargs(field_name, model_field):
     if model_field.has_default() or model_field.blank or model_field.null:
         kwargs['required'] = False
 
-    if model_field.null and not isinstance(model_field, models.NullBooleanField):
+    is_null_boolean_field = isinstance(model_field, models.NullBooleanField)
+    if (model_field.null and not is_null_boolean_field) or (model_field.choices and is_null_boolean_field):
         kwargs['allow_null'] = True
 
     if model_field.blank and (isinstance(model_field, models.CharField) or