diff --git a/elasticsearch_django/migrations/0001_initial.py b/elasticsearch_django/migrations/0001_initial.py
index 45d0b38..97a1297 100644
--- a/elasticsearch_django/migrations/0001_initial.py
+++ b/elasticsearch_django/migrations/0001_initial.py
@@ -22,7 +22,7 @@ class Migration(migrations.Migration):
                 ('total_hits', models.IntegerField(default=0, help_text='Total number of matches found for the query (!= the hits returned).')),
                 ('reference', models.CharField(default='', help_text='Custom reference used to identify and group related searches.', max_length=100, blank=True)),
                 ('executed_at', models.DateTimeField(help_text='When the search was executed - set via execute() method.')),
-                ('user', models.ForeignKey(related_name='search_queries', blank=True, to=settings.AUTH_USER_MODEL, help_text='The user who made the search query (nullable).', null=True)),
+                ('user', models.ForeignKey(related_name='search_queries', blank=True, to=settings.AUTH_USER_MODEL, help_text='The user who made the search query (nullable).', null=True, on_delete=models.SET_NULL)),
             ],
         ),
     ]
diff --git a/elasticsearch_django/models.py b/elasticsearch_django/models.py
index 756b432..f8c2d07 100644
--- a/elasticsearch_django/models.py
+++ b/elasticsearch_django/models.py
@@ -117,7 +117,7 @@ def from_search_query(self, search_query):
 
         """
         hits = search_query.hits
-        score_sql = self._raw_sql([(h['id'], h['score']) for h in hits])
+        score_sql = self._raw_sql([(h['id'], h['score'] or 0) for h in hits])
         rank_sql = self._raw_sql([(hits[i]['id'], i) for i in range(len(hits))])
         return (
             self.get_queryset()
@@ -367,7 +367,8 @@ class SearchQuery(models.Model):
         settings.AUTH_USER_MODEL,
         related_name='search_queries',
         blank=True, null=True,
-        help_text="The user who made the search query (nullable)."
+        help_text="The user who made the search query (nullable).",
+        on_delete=models.SET_NULL
     )
     index = models.CharField(
         max_length=100,
diff --git a/elasticsearch_django/tests/test_models.py b/elasticsearch_django/tests/test_models.py
index 12915c5..00a38b9 100644
--- a/elasticsearch_django/tests/test_models.py
+++ b/elasticsearch_django/tests/test_models.py
@@ -220,6 +220,7 @@ def test__raw_sql(self):
     @mock.patch('django.db.models.query.QuerySet')
     def test_from_search_query(self, mock_qs):
         """Test the from_search_query method."""
+        self.maxDiff = None
         sq = SearchQuery(hits=[{'id': 1, 'score': 1}, {'id': 2, 'score': 2}])
         qs = TestModel.objects.from_search_query(sq)
         self.assertEqual(
@@ -231,6 +232,18 @@ def test_from_search_query(self, mock_qs):
             '"elasticsearch_django_testmodel"."id" IN (1, 2) ORDER BY "search_rank" ASC'
         )
 
+        # test with a null score - new in v5
+        sq = SearchQuery(hits=[{'id': 1, 'score': None}, {'id': 2, 'score': 2}])
+        qs = TestModel.objects.from_search_query(sq)
+        self.assertEqual(
+            str(qs.query),
+            'SELECT "elasticsearch_django_testmodel"."id", '
+            '(SELECT CASE elasticsearch_django_testmodel."id" WHEN 1 THEN 0 WHEN 2 THEN 2 ELSE 0 END) '  # noqa
+            'AS "search_score", (SELECT CASE elasticsearch_django_testmodel."id" WHEN 1 THEN 0 WHEN 2 '  # noqa
+            'THEN 1 ELSE 0 END) AS "search_rank" FROM "elasticsearch_django_testmodel" WHERE '
+            '"elasticsearch_django_testmodel"."id" IN (1, 2) ORDER BY "search_rank" ASC'
+        )
+
 
 class SearchQueryTests(TestCase):
 
diff --git a/urls.py b/urls.py
index 039739a..5d43f33 100644
--- a/urls.py
+++ b/urls.py
@@ -5,5 +5,5 @@
 admin.autodiscover()
 
 urlpatterns = [
-    url(r'^admin/', include(admin.site.urls)),
+    url(r'^admin/', include(admin.site.urls,)),
 ]