diff --git a/VERSION b/VERSION
index 4a36342..fd2a018 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.0.0
+3.1.0
diff --git a/lib/spira/base.rb b/lib/spira/base.rb
index 63d6fbf..6bf3e5a 100644
--- a/lib/spira/base.rb
+++ b/lib/spira/base.rb
@@ -32,8 +32,6 @@ class Base
     # @return [RDF::URI]
     attr_reader :subject
 
-    attr_accessor :attributes
-
     class << self
       attr_reader :reflections, :properties
 
@@ -119,21 +117,26 @@ def id
     # @see RDF::Node#as
     def initialize(props = {}, options = {})
       @subject = props.delete(:_subject) || RDF::Node.new
+      @attrs = {}
 
-      @attributes = {}
       reload props
 
       yield self if block_given?
     end
 
+    # Returns the attributes
+    def attributes
+      @attrs
+    end
+
     # Freeze the attributes hash such that associations are still accessible, even on destroyed records.
     def freeze
-      @attributes.freeze; self
+      @attrs.freeze; self
     end
 
     # Returns +true+ if the attributes hash has been frozen.
     def frozen?
-      @attributes.frozen?
+      @attrs.frozen?
     end
 
     ##
@@ -257,7 +260,7 @@ def to_node
     # @param [RDF::Resource] new_subject
     # @return [Spira::Base] copy
     def copy(new_subject)
-      self.class.new(attributes.merge(:_subject => new_subject))
+      self.class.new(@attrs.merge(:_subject => new_subject))
     end
 
     ##
@@ -284,20 +287,19 @@ def assign_attributes(attrs)
     private
 
     def reset_changes
-      @previously_changed = changes
-      @changed_attributes.clear
+      clear_changes_information
     end
 
     def write_attribute(name, value)
       name = name.to_s
       if self.class.properties[name]
-        if attributes[name].is_a?(Promise)
-          changed_attributes[name] = attributes[name] unless changed_attributes.include?(name)
-          attributes[name] = value
+        if @attrs[name].is_a?(Promise)
+          changed_attributes[name] = @attrs[name] unless changed_attributes.include?(name)
+          @attrs[name] = value
         else
           if value != read_attribute(name)
             attribute_will_change!(name)
-            attributes[name] = value
+            @attrs[name] = value
           end
         end
       else
@@ -309,7 +311,7 @@ def write_attribute(name, value)
     # Get the current value for the given attribute
     #
     def read_attribute(name)
-      value = attributes[name.to_s]
+      value = @attrs[name.to_s]
 
       refl = self.class.reflections[name]
       if refl && !value
diff --git a/spec/base_uri_spec.rb b/spec/base_uri_spec.rb
index 04cda57..f873220 100644
--- a/spec/base_uri_spec.rb
+++ b/spec/base_uri_spec.rb
@@ -74,7 +74,7 @@ class ::HashBaseURITest < Spira::Base
   context "classes without a base URI" do
     before :all do
       class ::NoBaseURITest < Spira::Base
-        property :name, :predicate => RDFS.label
+        property :name, :predicate => RDF::RDFS.label
       end
     end
 
diff --git a/spec/non_model_data_spec.rb b/spec/non_model_data_spec.rb
index e761853..96fd852 100644
--- a/spec/non_model_data_spec.rb
+++ b/spec/non_model_data_spec.rb
@@ -7,7 +7,7 @@ class ::ExtraDataTest < Spira::Base
       configure :base_uri => "http://example.org/example"
 
       property :property, :predicate => RDF::Vocab::FOAF.age, :type => Integer
-      has_many :list,     :predicate => RDFS.label
+      has_many :list,     :predicate => RDF::RDFS.label
     end
   end
   let(:extra_repo) {RDF::Repository.load(fixture('non_model_data.nt'))}
diff --git a/spec/psych_spec.rb b/spec/psych_spec.rb
index ebb6ba5..7bfbb9a 100644
--- a/spec/psych_spec.rb
+++ b/spec/psych_spec.rb
@@ -8,12 +8,12 @@
   before :all do
     class PsychPerson < Spira::Base
       configure :base_uri => "http://example.org/example/people"
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
       property :age,  :predicate => RDF::Vocab::FOAF.age,  :type => Integer
     end
-    
+
     class PsychEmployee < Spira::Base
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
       property :age,  :predicate => RDF::Vocab::FOAF.age, :type => Integer
     end
 
diff --git a/spec/rdf_types_spec.rb b/spec/rdf_types_spec.rb
index f7e37d3..93ffec1 100644
--- a/spec/rdf_types_spec.rb
+++ b/spec/rdf_types_spec.rb
@@ -1,5 +1,5 @@
 require "spec_helper"
-# These classes are to test finding based on rdfs.type
+# These classes are to test finding based on RDF::RDFS.type
 
 
 class Cars < RDF::Vocabulary('http://example.org/cars/')
@@ -19,16 +19,16 @@ class Cars < RDF::Vocabulary('http://example.org/cars/')
   before :all do
     class ::Car < Spira::Base
       type Cars.car
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
     end
-    
+
     class ::Van < Spira::Base
       type Cars.van
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
     end
-    
+
     class ::Wagon < Spira::Base
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
     end
 
     class ::MultiCar < Spira::Base
@@ -51,7 +51,7 @@ class ::XYZ < Spira::Base
     it "should provide a class method which returns the type" do
       expect(Car).to respond_to :type
     end
-    
+
     it "should return the correct type" do
       expect(Car.type).to eql Cars.car
     end
diff --git a/spec/relations_spec.rb b/spec/relations_spec.rb
index 5480f59..4d1e9b2 100644
--- a/spec/relations_spec.rb
+++ b/spec/relations_spec.rb
@@ -3,20 +3,20 @@
 describe "Spira resources" do
 
   before :all do
-    
+
     class ::CDs < RDF::Vocabulary('http://example.org/')
       property :artist
       property :cds
       property :artists
       property :has_cd
     end
-    
+
     class ::CD < Spira::Base
       configure :base_uri => CDs.cds
       property :name,   :predicate => RDF::Vocab::DC.title,   :type => String
       property :artist, :predicate => CDs.artist, :type => 'Artist'
     end
-    
+
     class ::Artist < Spira::Base
       configure :base_uri => CDs.artists
       property :name, :predicate => RDF::Vocab::DC.title, :type => String
@@ -45,7 +45,7 @@ class ::RootNSTest < Spira::Base
         test.name = RootNSTest.new
         test.name.save!
         test.save!
-        
+
         test = subject.as(RootNSTest)
         expect(test.name).to be_a RootNSTest
       end
@@ -86,7 +86,7 @@ module ::NSTestA
           class A < Spira::Base
           end
         end
-      end 
+      end
 
       it "should find a class based on the string version of the name" do
         test = NSTest::Z.new
@@ -129,7 +129,7 @@ class A < Spira::Base
   context "with a one-to-many relationship" do
     subject(:artist) {Artist.for "nirvana"}
     subject(:cd) {CD.for 'nevermind'}
-  
+
     before :each do
       Spira.repository = RDF::Repository.load(fixture('relations.nt'))
       @cd = CD.for 'nevermind'
@@ -188,7 +188,7 @@ class A < Spira::Base
     before {Spira.repository = invalid_repo}
 
     context "when accessing a field named for a non-existant class" do
-      
+
       before do
         class ::RelationsTestA < Spira::Base
           configure :base_uri => CDs.cds
@@ -218,7 +218,7 @@ class ::RelationsTestB < Spira::Base
           property :invalid, :predicate => RDF::Vocab::DC.title, :type => 'Object'
         end
       end
-    
+
       it "should should raise a TypeError when saving an object with the invalid property" do
         expect { RelationsTestB.new(:invalid => Object.new).save! }.to raise_error TypeError
       end
diff --git a/spec/update_spec.rb b/spec/update_spec.rb
index 54bbae5..c6294c4 100644
--- a/spec/update_spec.rb
+++ b/spec/update_spec.rb
@@ -7,7 +7,7 @@
   before :all do
     class ::UpdateTest < Spira::Base
       configure :base_uri => "http://example.org/example/people"
-      property :name, :predicate => RDFS.label
+      property :name, :predicate => RDF::RDFS.label
       property :age,  :predicate => RDF::Vocab::FOAF.age,  :type => Integer
     end
   end
diff --git a/spec/validations_spec.rb b/spec/validations_spec.rb
index 82fd78c..0ed4974 100644
--- a/spec/validations_spec.rb
+++ b/spec/validations_spec.rb
@@ -8,7 +8,7 @@
   class ::Bank < Spira::Base
     configure :default_vocabulary => RDF::URI.new('http://example.org/banks/vocab')
 
-    property :title, :predicate => RDFS.label
+    property :title, :predicate => RDF::RDFS.label
     property :balance, :type => Integer
 
     validate :validate_bank