diff --git a/mongoengine/queryset.py b/mongoengine/queryset.py
index 7969c196..662fa8c3 100644
--- a/mongoengine/queryset.py
+++ b/mongoengine/queryset.py
@@ -892,7 +892,7 @@ class QuerySet(object):
                 var total = 0.0;
                 var num = 0;
                 db[collection].find(query).forEach(function(doc) {
-                    if (doc[averageField]) {
+                    if (doc[averageField] !== undefined) {
                         total += doc[averageField];
                         num += 1;
                     }
diff --git a/tests/queryset.py b/tests/queryset.py
index 2f86953d..0c6c3ca4 100644
--- a/tests/queryset.py
+++ b/tests/queryset.py
@@ -960,11 +960,14 @@ class QuerySetTest(unittest.TestCase):
     def test_average(self):
         """Ensure that field can be averaged correctly.
         """
+        self.Person(name='person', age=0).save()
+        self.assertEqual(int(self.Person.objects.average('age')), 0)
+
         ages = [23, 54, 12, 94, 27]
         for i, age in enumerate(ages):
             self.Person(name='test%s' % i, age=age).save()
 
-        avg = float(sum(ages)) / len(ages)
+        avg = float(sum(ages)) / (len(ages) + 1) # take into account the 0
         self.assertAlmostEqual(int(self.Person.objects.average('age')), avg)
 
         self.Person(name='ageless person').save()
@@ -1340,5 +1343,6 @@ class QTest(unittest.TestCase):
         self.assertEqual(Post.objects.filter(created_user=user).count(), 1)
         self.assertEqual(Post.objects.filter(Q(created_user=user)).count(), 1)
 
+
 if __name__ == '__main__':
     unittest.main()