diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..c043eea
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.2.1
diff --git a/.rvmrc b/.rvmrc
deleted file mode 100644
index a459cd0..0000000
--- a/.rvmrc
+++ /dev/null
@@ -1 +0,0 @@
-rvm --create use ruby-2.1.1@resort
diff --git a/Readme.md b/Readme.md
index f45d114..bd1dff9 100644
--- a/Readme.md
+++ b/Readme.md
@@ -1,6 +1,6 @@
 #resort [![Build Status](https://secure.travis-ci.org/codegram/resort.png)](http://travis-ci.org/codegram/resort)
 
-Resort provides sorting capabilities to your Rails 3 models.
+Resort provides sorting capabilities to your Rails models.
 
 ##Install
 
@@ -72,8 +72,10 @@ Moreover, now a `product` responds to the following methods:
 
 * `first?` — Returns true if the element is the first of the tree.
 * `append_to(other_element)` — Appends the element _after_ another element.
-* `next` — Returns the next element in the list
-* `previous` — Returns the previous element in the list
+* `prepend` — Moves the elemnt to the beggining of the list (sets it as
+  first).
+* `next` — Returns the next element in the list.
+* `previous` — Returns the previous element in the list.
 
 And the class Product has a new scope named `ordered` that returns the
 products in order.
diff --git a/lib/generators/active_record/resort_generator.rb b/lib/generators/active_record/resort_generator.rb
index 2c00a54..46a5ed9 100644
--- a/lib/generators/active_record/resort_generator.rb
+++ b/lib/generators/active_record/resort_generator.rb
@@ -17,7 +17,7 @@ def self.next_migration_number(dirname)
           "%.3d" % (current_migration_number(dirname) + 1)
         end
       end
-      
+
       desc "Creates a Resort migration."
       source_root File.expand_path("../templates", __FILE__)
 
diff --git a/lib/resort.rb b/lib/resort.rb
index fff3b10..f8dde65 100644
--- a/lib/resort.rb
+++ b/lib/resort.rb
@@ -84,7 +84,7 @@ def last_in_order
         all.where(:next_id => nil).first
       end
 
-      
+
       # Returns eager-loaded Components in order.
       #
       # OPTIMIZE: Use IdentityMap when available
@@ -102,7 +102,7 @@ def ordered
         end
 
         raise "Multiple or no first items in the list where found. Consider defining a siblings method" if ordered_elements.length != 1 && elements.length > 0
-        
+
         elements.length.times do
           ordered_elements << elements[ordered_elements.last.next_id]
         end
@@ -144,7 +144,7 @@ def include_in_list!
         self.class.transaction do
           self.lock!
           _siblings.count > 0 ? last!\
-                              : prepend
+            : prepend
         end
       end
 
@@ -156,8 +156,8 @@ def prepend
           if _siblings.count > 0
             delete_from_list
             old_first = _siblings.first_in_order
-            raise(ActiveRecord::RecordNotSaved) unless self.update_attribute(:next_id, old_first.id)
-            raise(ActiveRecord::RecordNotSaved) unless old_first.update_attribute(:first, false)
+            raise(ActiveRecord::RecordNotSaved.new("[Resort] - Couldn't set next_id from previous first element.")) unless self.update_attribute(:next_id, old_first.id)
+            raise(ActiveRecord::RecordNotSaved.new("[Resort] - Couldn't reset previous firt element")) unless old_first.update_attribute(:first, false)
           end
           raise(ActiveRecord::RecordNotSaved) unless self.update_attribute(:first, true)
         end
@@ -179,10 +179,10 @@ def append_to(another)
           another.lock!
           delete_from_list
           if self.next_id or (another && another.next_id)
-            raise(ActiveRecord::RecordNotSaved) unless self.update_attribute(:next_id, another.next_id)
+            raise(ActiveRecord::RecordNotSaved.new("[Resort] - Couldn't append element")) unless self.update_attribute(:next_id, another.next_id)
           end
           if another
-            raise(ActiveRecord::RecordNotSaved) unless another.update_attribute(:next_id, self.id)
+            raise(ActiveRecord::RecordNotSaved.new("[Resort] - Couldn't set this element to another's next")) unless another.update_attribute(:next_id, self.id)
           end
         end
       end
@@ -200,8 +200,8 @@ def delete_from_list
           raise(ActiveRecord::RecordNotSaved) unless p.update_attribute(:next_id, self.next_id)
         end
         unless frozen?
-          self.first = false 
-          self.next = nil 
+          self.first = false
+          self.next = nil
           save!
         end
       end
diff --git a/resort.gemspec b/resort.gemspec
index 99aa8a1..e495ecc 100644
--- a/resort.gemspec
+++ b/resort.gemspec
@@ -14,7 +14,7 @@ Gem::Specification.new do |s|
 
   s.rubyforge_project = "resort"
 
-  s.add_runtime_dependency 'activerecord', '>= 4.0.4'
+  s.add_runtime_dependency 'activerecord', '~> 4'
   s.add_development_dependency 'sqlite3'
   s.add_development_dependency 'rspec', '~> 2.14.1'
   s.add_development_dependency 'yard'