diff --git a/django/contrib/auth/models.py b/django/contrib/auth/models.py
index eb39868ca9..4e1584970c 100644
--- a/django/contrib/auth/models.py
+++ b/django/contrib/auth/models.py
@@ -149,6 +149,8 @@ class UserManager(models.Manager):
         Creates and saves a User with the given username, email and password.
         """
         now = timezone.now()
+        if not username:
+            raise ValueError('The given username must be set')
         email = UserManager.normalize_email(email)
         user = self.model(username=username, email=email,
                           is_staff=False, is_active=True, is_superuser=False,
diff --git a/django/contrib/auth/tests/models.py b/django/contrib/auth/tests/models.py
index 2d570aee15..25121966a0 100644
--- a/django/contrib/auth/tests/models.py
+++ b/django/contrib/auth/tests/models.py
@@ -91,3 +91,8 @@ class UserManagerTestCase(TestCase):
     def test_create_user_email_domain_normalize_with_whitespace(self):
         returned = UserManager.normalize_email('email\ with_whitespace@D.COM')
         self.assertEquals(returned, 'email\ with_whitespace@d.com')
+
+    def test_empty_username(self):
+        self.assertRaisesMessage(ValueError,
+                                 'The given username must be set',
+                                  User.objects.create_user, username='')
diff --git a/docs/topics/auth.txt b/docs/topics/auth.txt
index 08a8f342c5..6b262be47f 100644
--- a/docs/topics/auth.txt
+++ b/docs/topics/auth.txt
@@ -280,7 +280,9 @@ Manager functions
     .. method:: models.UserManager.create_user(username, email=None, password=None)
 
         .. versionchanged:: 1.4
-           The ``email`` parameter was made optional.
+           The ``email`` parameter was made optional. The username
+           parameter is now checked for emptiness and raises a
+           :exc:`ValueError` in case of a negative result.
 
         Creates, saves and returns a :class:`~django.contrib.auth.models.User`.