diff --git a/lib/disposable/twin/changed.rb b/lib/disposable/twin/changed.rb
index f386ff2..bb5938b 100644
--- a/lib/disposable/twin/changed.rb
+++ b/lib/disposable/twin/changed.rb
@@ -1,41 +1,32 @@
 module Disposable::Twin::Changed
-  class Changes < Hash
-    def changed?(name=nil)
-      return true if name.nil? and values.find { |val| val == true } # TODO: this could be speed-improved, of course.
+  def changes(name=nil)
+    _find_changed_twins!(_changes)
 
-      !! self[name.to_s]
-    end
-  end
-
-
-  def changed?(*args) # not recommended for external use?
-    changed.changed?(*args)
+    return _changes unless name
+    _changes[name.to_s]
   end
 
-# FIXME: can we make #changed the only public concept? so we don't need to find twice?
+  def changed?(name=nil)
+    _find_changed_twins!(_changes)
 
-  # this is usually called only once in Sync::SkipUnchanged, per twin.
-  def changed
-    _find_changed_twins!(@_changes)
-
-    @_changes
+    (name.nil? && _changes.values.any?) || _changes.has_key?(name.to_s)
   end
 
 private
-  def initialize(model, *args)
-    super         # Setup#initialize.
-    @_changes = Changes.new # override changed from initialize.
-  end
 
-  def _changed
-    @_changes ||= Changes.new # FIXME: why do we need to re-initialize here?
+  attr_reader :_changes
+  def initialize(model, *args)
+    super          # Setup#initialize.
+    @_changes = {} # override changed from initialize.
   end
 
   def write_property(name, value, dfn)
     old_value = field_read(name)
+    return if old_value == value
 
     super.tap do
-      _changed[name.to_s] = old_value != value
+      @_changes ||= {}
+      _changes[name.to_s] = [old_value, value]
     end
   end
 
@@ -44,7 +35,14 @@ def _find_changed_twins!(changes) # FIXME: this will change soon. don't touch.
       next unless twin = send(dfn.getter)
       next unless twin.changed?
 
-      changes[dfn[:name]] = true
+      if twin.is_a?(Disposable::Twin::Collection)
+        changes[dfn[:name]] = []
+        twin.each do |item|
+          changes[dfn[:name]] << item.changes
+        end
+      else
+        changes[dfn[:name]] = twin.changes
+      end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/test/twin/changed_test.rb b/test/twin/changed_test.rb
index 1121642..1e7fe43 100644
--- a/test/twin/changed_test.rb
+++ b/test/twin/changed_test.rb
@@ -63,17 +63,53 @@ class Album < Disposable::Twin
     twin.artist.name = "No Fun At All"
 
     expect(twin.changed?(:name)).must_equal true
+    expect(twin.changes(:name)).must_equal ["The Rest Is Silence", "Out Of Bounds"]
+    expect(twin.changes).must_equal({
+      "name" => ["The Rest Is Silence", "Out Of Bounds"],
+      "artist" => { "name" => ["Randy", "No Fun At All"] },
+      "songs" => [
+        {"title" => ["Broken", "I Have Seen"]},
+        {
+          "title" => ["Broken", "In A Rhyme"],
+          "composer" => {
+            "name" => [2, "Ingemar Jansson & Mikael Danielsson"]
+          }
+        }
+      ]
+    })
     expect(twin.changed?).must_equal true
 
     expect(twin.songs[0].changed?).must_equal true
     expect(twin.songs[0].changed?(:title)).must_equal true
+    expect(twin.songs[0].changes(:title)).must_equal ["Broken", "I Have Seen"]
+    expect(twin.songs[0].changes).must_equal({
+      "title" => ["Broken", "I Have Seen"]
+    })
+
     expect(twin.songs[1].changed?).must_equal true
     expect(twin.songs[1].changed?(:title)).must_equal true
+    expect(twin.songs[1].changes(:title)).must_equal ["Broken", "In A Rhyme"]
+    expect(twin.songs[1].changes).must_equal({
+      "title" => ["Broken", "In A Rhyme"],
+      "composer" => {
+        "name" => [2, "Ingemar Jansson & Mikael Danielsson"]
+      }
+    })
 
     expect(twin.songs[1].composer.changed?(:name)).must_equal true
+    expect(twin.songs[1].composer.changes(:name)).must_equal(
+      [2, "Ingemar Jansson & Mikael Danielsson"]
+    )
+    expect(twin.songs[1].composer.changes).must_equal({
+      "name" => [2, "Ingemar Jansson & Mikael Danielsson"]
+    })
     expect(twin.songs[1].composer.changed?).must_equal true
 
     expect(twin.artist.changed?(:name)).must_equal true
+    expect(twin.artist.changes(:name)).must_equal ["Randy", "No Fun At All"]
+    expect(twin.artist.changes).must_equal({
+      "name" => ["Randy", "No Fun At All"]
+    })
     expect(twin.artist.changed?).must_equal true
 
     # you can also ask for nested twins by name.
diff --git a/test/twin/struct_test.rb b/test/twin/struct_test.rb
index 2d39bde..7929847 100644
--- a/test/twin/struct_test.rb
+++ b/test/twin/struct_test.rb
@@ -26,7 +26,7 @@ class Song < Disposable::Twin
   it { expect(Song.new({number: 3}, {cool?: true}).number).must_equal 3 }
 
   # with string key and false value
-  it { Song.new('number' => 3, 'cool?' => false).cool?.must_equal false }
+  it { expect(Song.new('number' => 3, 'cool?' => false).cool?).must_equal false }
 
 
   describe "writing" do