diff --git a/cqlengine/query.py b/cqlengine/query.py
index e6cccc9f..a62b172d 100644
--- a/cqlengine/query.py
+++ b/cqlengine/query.py
@@ -417,7 +417,9 @@ class QuerySet(object):
 
         #get defined fields and their column names
         for name, col in self.model._columns.items():
-            value_pairs += [(col.db_field_name, values.get(name))]
+            val = values.get(name)
+            if val is None: continue
+            value_pairs += [(col.db_field_name, val)]
 
         #construct query string
         field_names = zip(*value_pairs)[0]
@@ -435,14 +437,13 @@ class QuerySet(object):
         #TODO: delete deleted / nulled columns
         deleted = [k for k,v in instance._values.items() if v.deleted]
         if deleted:
-            import ipdb; ipdb.set_trace()
             del_fields = [self.model._columns[f] for f in deleted]
             del_fields = [f.db_field_name for f in del_fields if not f.primary_key]
             pks = self.model._primary_keys
             qs = ['DELETE {}'.format(', '.join(del_fields))]
             qs += ['FROM {}'.format(self.column_family_name)]
             qs += ['WHERE']
-            eq = lambda col: '{0} = :{0}'.format(v.db_field_name)
+            eq = lambda col: '{0} = :{0}'.format(v.column.db_field_name)
             qs += [' AND '.join([eq(f) for f in pks.values()])]
             qs = ' '.join(qs)
 
diff --git a/cqlengine/tests/model/test_model_io.py b/cqlengine/tests/model/test_model_io.py
index 09a72809..f408e46c 100644
--- a/cqlengine/tests/model/test_model_io.py
+++ b/cqlengine/tests/model/test_model_io.py
@@ -9,7 +9,7 @@ from cqlengine import columns
 
 class TestModel(Model):
     count   = columns.Integer()
-    text    = columns.Text()
+    text    = columns.Text(required=False)
 
 class TestModelIO(BaseCassEngTestCase):
 
@@ -57,4 +57,12 @@ class TestModelIO(BaseCassEngTestCase):
     def test_column_deleting_works_properly(self):
         """
         """
+        tm = TestModel.objects.create(count=8, text='123456789')
+        tm.text = None
+        tm.save()
+
+        tm2 = TestModel.objects(id=tm.pk).first()
+        assert tm2.text is None
+        assert tm2._values['text'].initial_value is None
+