diff --git a/lib/resort.rb b/lib/resort.rb
index 9a8518c..b66e235 100644
--- a/lib/resort.rb
+++ b/lib/resort.rb
@@ -62,7 +62,7 @@ def included(base)
         base.send :include, InstanceMethods
 
         base.has_one :previous, class_name: base.name, foreign_key: 'next_id', inverse_of: :next
-        base.belongs_to :next, class_name: base.name, inverse_of: :previous
+        base.belongs_to :next, class_name: base.name, inverse_of: :previous, optional: true
 
         base.after_create :include_in_list!
         base.after_destroy :delete_from_list
@@ -142,6 +142,7 @@ def siblings
       # empty list.
       def include_in_list!
         self.class.transaction do
+          save
           lock!
           _siblings.count > 0 ? last!\
             : prepend
@@ -151,6 +152,7 @@ def include_in_list!
       # Puts the object in the first position of the list.
       def prepend
         self.class.transaction do
+          save
           lock!
           return if first?
           if _siblings.count > 0
@@ -166,6 +168,7 @@ def prepend
       # Puts the object in the last position of the list.
       def push
         self.class.transaction do
+          save
           lock!
           append_to(_siblings.last_in_order) unless last?
         end
@@ -174,8 +177,10 @@ def push
       # Puts the object right after another object in the list.
       def append_to(another)
         self.class.transaction do
+          save
           lock!
           return if another.next_id == id
+          another.save
           another.lock!
           delete_from_list
           if next_id || (another && another.next_id)
@@ -193,6 +198,7 @@ def last?
 
       def last!
         self.class.transaction do
+          save
           lock!
           raise(ActiveRecord::RecordNotSaved) unless _siblings.last_in_order.update_attribute(:next_id, id)
         end
@@ -202,9 +208,11 @@ def last!
 
       def delete_from_list
         if first? && self.next
+          self.next.save
           self.next.lock!
           raise(ActiveRecord::RecordNotSaved) unless self.next.update_attribute(:first, true)
         elsif previous
+          previous.save
           previous.lock!
           p = previous
           self.previous = nil unless frozen?