diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 9be6e83ee1..b7d0c8cb90 100644
--- a/django/db/backends/__init__.py
+++ b/django/db/backends/__init__.py
@@ -266,6 +266,10 @@ class BaseDatabaseFeatures(object):
     # Does the backend distinguish between '' and None?
     interprets_empty_strings_as_nulls = False
 
+    # Does the backend allow inserting duplicate rows when a unique_together
+    # constraint exists, but one of the unique_together columns is NULL?
+    ignores_nulls_in_unique_constraints = True
+
     can_use_chunked_reads = True
     can_return_id_from_insert = False
     uses_autocommit = False
diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 442378cd28..b327e453e0 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -76,6 +76,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
     supports_timezones = False
     supports_bitwise_or = False
     can_defer_constraint_checks = True
+    ignores_nulls_in_unique_constraints = False
 
 class DatabaseOperations(BaseDatabaseOperations):
     compiler_module = "django.db.backends.oracle.compiler"
diff --git a/tests/modeltests/model_formsets/tests.py b/tests/modeltests/model_formsets/tests.py
index 5e6d88ebe8..5c35a589bf 100644
--- a/tests/modeltests/model_formsets/tests.py
+++ b/tests/modeltests/model_formsets/tests.py
@@ -7,7 +7,7 @@ from django import forms
 from django.db import models
 from django.forms.models import (_get_foreign_key, inlineformset_factory,
     modelformset_factory, modelformset_factory)
-from django.test import TestCase
+from django.test import TestCase, skipUnlessDBFeature
 
 from modeltests.model_formsets.models import (
     Author, BetterAuthor, Book, BookWithCustomPK, Editor,
@@ -577,10 +577,13 @@ class ModelFormsetTest(TestCase):
         self.assertEqual(book1.title, 'Flowers of Evil')
         self.assertEqual(book1.notes, 'English translation of Les Fleurs du Mal')
 
+    @skipUnlessDBFeature('ignores_nulls_in_unique_constraints')
+    def test_inline_formsets_with_nullable_unique_together(self):
         # Test inline formsets where the inline-edited object has a
         # unique_together constraint with a nullable member
 
         AuthorBooksFormSet4 = inlineformset_factory(Author, BookWithOptionalAltEditor, can_delete=False, extra=2)
+        author = Author.objects.create(pk=1, name='Charles Baudelaire')
 
         data = {
             'bookwithoptionalalteditor_set-TOTAL_FORMS': '2', # the number of forms rendered