diff --git a/mongoengine/base.py b/mongoengine/base.py
index 909ed6cd..ea0f98a4 100644
--- a/mongoengine/base.py
+++ b/mongoengine/base.py
@@ -381,8 +381,8 @@ class DocumentMetaclass(type):
                     attr_value.db_field = attr_name
                 doc_fields[attr_name] = attr_value
         attrs['_fields'] = doc_fields
-        attrs['_db_field_map'] = dict([(k, v.db_field) for k, v in doc_fields.items()])
-        attrs['_reverse_db_field_map'] = dict([(v.db_field, k) for k, v in doc_fields.items()])
+        attrs['_db_field_map'] = dict([(k, v.db_field) for k, v in doc_fields.items() if k!=v.db_field])
+        attrs['_reverse_db_field_map'] = dict([(v, k) for k, v in attrs['_db_field_map'].items()])
 
         new_class = super_new(cls, name, bases, attrs)
         for field in new_class._fields.values():
@@ -577,6 +577,7 @@ class BaseDocument(object):
         signals.pre_init.send(self.__class__, document=self, values=values)
 
         self._data = {}
+        self._initialised = False
         # Assign default values to instance
         for attr_name, field in self._fields.items():
             value = getattr(self, attr_name, None)
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 3234160d..b2f1e2a2 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -911,14 +911,26 @@ class SequenceField(IntField):
 
         if instance is None:
             return self
+
         if not instance._data:
             return
+
         value = instance._data.get(self.name)
+
         if not value and instance._initialised:
             value = self.generate_new_value()
             instance._data[self.name] = value
+            instance._mark_as_changed(self.name)
+
         return value
 
+    def __set__(self, instance, value):
+        
+        if value is None and instance._initialised:
+            value = self.generate_new_value()
+
+        return super(SequenceField, self).__set__(instance, value)
+
     def to_python(self, value):
         if value is None:
             value = self.generate_new_value()
diff --git a/tests/fields.py b/tests/fields.py
index 1f070ae1..f8aeb86c 100644
--- a/tests/fields.py
+++ b/tests/fields.py
@@ -1425,6 +1425,32 @@ class FieldTest(unittest.TestCase):
         c = self.db['mongoengine.counters'].find_one({'_id': 'person.id'})
         self.assertEqual(c['next'], 10)
 
+    def test_sequence_fields_reload(self):
+        class Animal(Document):
+            counter = SequenceField()
+            type = StringField()
+
+        self.db['mongoengine.counters'].drop()
+        Animal.drop_collection()
+
+        a = Animal(type="Boi")
+        a.save()
+
+        self.assertEqual(a.counter, 1)
+        a.reload()
+        self.assertEqual(a.counter, 1)
+
+        a.counter = None
+        self.assertEqual(a.counter, 2)
+        a.save()
+
+        self.assertEqual(a.counter, 2)
+        
+        a = Animal.objects.first()
+        self.assertEqual(a.counter, 2)
+        a.reload()
+        self.assertEqual(a.counter, 2)
+
     def test_multiple_sequence_fields_on_docs(self):
 
         class Animal(Document):