diff --git a/polls/models.py b/polls/models.py
index 101fb9b..f765548 100644
--- a/polls/models.py
+++ b/polls/models.py
@@ -27,7 +27,7 @@ class Question(models.Model):
     """
 
     question_text = models.CharField(max_length=200)
-    pub_date = models.DateTimeField("date published", default=timezone.now)
+    pub_date = models.DateTimeField("date published", auto_now_add=True)
     end_date = models.DateTimeField("date ended", null=True)
 
     def was_published_recently(self):
diff --git a/polls/tests.py b/polls/tests.py
index d378745..9141b10 100644
--- a/polls/tests.py
+++ b/polls/tests.py
@@ -26,7 +26,6 @@ class QuestionModelTests(TestCase):
         old_question = Question(pub_date=time)
         self.assertIs(old_question.was_published_recently(), False)
 
-
     def test_was_published_recently_with_recent_question(self):
         """
         was_published_recently() returns True for questions whose pub_date
@@ -36,7 +35,6 @@ class QuestionModelTests(TestCase):
         recent_question = Question(pub_date=time)
         self.assertIs(recent_question.was_published_recently(), True)
 
-
     def test_is_published_with_future_question(self):
         """
         is_published() should return False for questions whos pub_date is in the
@@ -46,6 +44,18 @@ class QuestionModelTests(TestCase):
         future_question = Question(pub_date=future_date)
         self.assertIs(future_question.is_published(), False)
 
+    def test_default_pub_date(self):
+        """
+        Questions with the default pub_date (now) are displayed on the index page.
+        """
+        question = Question.objects.create(question_text="Default pub date question.")
+        
+        response = self.client.get(reverse("polls:index"))
+        self.assertQuerySetEqual(
+            response.context["latest_question_list"],
+            [question],
+        )
+
     def test_is_published_with_past_question(self):
         """
         is_published() should return True for questions whose pub_date is in the
@@ -95,13 +105,15 @@ class QuestionModelTests(TestCase):
         self.assertIs(question.can_vote(), True)
 
 
-def create_question(question_text, days):
+def create_question(self, question_text, days, pub_date=None):
     """
     Create a question with the given `question_text` and published the
     given number of `days` offset to now (negative for questions published
     in the past, positive for questions that have yet to be published).
     """
-    time = timezone.now() + datetime.timedelta(days=days)
+    time = timezone.now() + timezone.timedelta(days=days)
+    if pub_date is not None:
+        time = pub_date
     return Question.objects.create(question_text=question_text, pub_date=time)
 
 
@@ -120,7 +132,9 @@ class QuestionIndexViewTests(TestCase):
         Questions with a pub_date in the past are displayed on the
         index page.
         """
-        question = create_question(question_text="Past question.", days=-30)
+        question = Question.objects.create(question_text="Past question.")
+        question.pub_date = timezone.now() - timezone.timedelta(days=30)
+        question.save()
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
             response.context["latest_question_list"],
@@ -132,7 +146,9 @@ class QuestionIndexViewTests(TestCase):
         Questions with a pub_date in the future aren't displayed on
         the index page.
         """
-        create_question(question_text="Future question.", days=30)
+        future_question = Question.objects.create(question_text="Future question.")
+        future_question.pub_date = timezone.now() + timezone.timedelta(days=30)
+        future_question.save()
         response = self.client.get(reverse("polls:index"))
         self.assertContains(response, "No polls are available.")
         self.assertQuerySetEqual(response.context["latest_question_list"], [])
@@ -142,20 +158,32 @@ class QuestionIndexViewTests(TestCase):
         Even if both past and future questions exist, only past questions
         are displayed.
         """
-        question = create_question(question_text="Past question.", days=-30)
-        create_question(question_text="Future question.", days=30)
+        past_question = Question.objects.create(question_text="Past question.")
+        past_question.pub_date = timezone.now() - timezone.timedelta(days=30)
+        past_question.save()
+
+        future_question = Question.objects.create(question_text="Future question.")
+        future_question.pub_date = timezone.now() + timezone.timedelta(days=30)
+        future_question.save()
+
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
             response.context["latest_question_list"],
-            [question],
+            [past_question],
         )
 
     def test_two_past_questions(self):
         """
         The questions index page may display multiple questions.
         """
-        question1 = create_question(question_text="Past question 1.", days=-30)
-        question2 = create_question(question_text="Past question 2.", days=-5)
+        question1 = Question.objects.create(question_text="Past question 1.")
+        question1.pub_date = timezone.now() - timezone.timedelta(days=30)
+        question1.save()
+
+        question2 = Question.objects.create(question_text="Past question 2.")
+        question2.pub_date = timezone.now() - timezone.timedelta(days=5)
+        question2.save()
+
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
             response.context["latest_question_list"],
@@ -169,7 +197,10 @@ class QuestionDetailViewTests(TestCase):
         The detail view of a question with a pub_date in the future
         returns a 404 not found.
         """
-        future_question = create_question(question_text="Future question.", days=5)
+        future_question = Question.objects.create(question_text="Future question.")
+        future_question.pub_date = timezone.now() + timezone.timedelta(days=5)
+        future_question.save()
+
         url = reverse("polls:detail", args=(future_question.id,))
         response = self.client.get(url)
         self.assertEqual(response.status_code, 404)
@@ -179,7 +210,10 @@ class QuestionDetailViewTests(TestCase):
         The detail view of a question with a pub_date in the past
         displays the question's text.
         """
-        past_question = create_question(question_text="Past Question.", days=-5)
+        past_question = Question.objects.create(question_text="Past Question.")
+        past_question.pub_date = timezone.now() - timezone.timedelta(days=5)
+        past_question.save()
+
         url = reverse("polls:detail", args=(past_question.id,))
         response = self.client.get(url)
         self.assertContains(response, past_question.question_text)