diff --git a/lib/json-api-vanilla/parser.rb b/lib/json-api-vanilla/parser.rb
index b24a3b9..3bb8a50 100644
--- a/lib/json-api-vanilla/parser.rb
+++ b/lib/json-api-vanilla/parser.rb
@@ -58,17 +58,12 @@ def self.build(hash)
 
     obj_hashes.each do |o_hash|
       klass = prepare_class(o_hash, superclass, container)
-      obj = klass.new
-      obj.type = o_hash['type']
-      obj.id = o_hash['id']
-      if o_hash['attributes']
-        o_hash['attributes'].each do |key, value|
-          set_key(obj, key, value, original_keys)
-        end
-      end
+      obj = prepare_object(o_hash, klass, original_keys)
+
       if o_hash['links']
         links[obj] = o_hash['links']
       end
+
       objects[[obj.type, obj.id]] = obj
     end
 
@@ -82,10 +77,22 @@ def self.build(hash)
             if data.is_a?(Array)
               # One-to-many relationship.
               ref = data.map do |ref_hash|
-                objects[[ref_hash['type'], ref_hash['id']]]
+                _ref = objects[[ref_hash['type'], ref_hash['id']]]
+
+                if _ref.nil?
+                  klass = prepare_class(ref_hash, superclass, container)
+                  _ref = prepare_object(ref_hash, klass)
+                end
+
+                _ref
               end
             else
               ref = objects[[data['type'], data['id']]]
+
+              if ref.nil?
+                klass = prepare_class(data, superclass, container)
+                ref = prepare_object(data, klass)
+              end
             end
           end
 
@@ -130,6 +137,18 @@ def self.prepare_class(hash, superclass, container)
     klass
   end
 
+  def self.prepare_object(hash, klass, original_keys = {})
+    (klass.new).tap do |obj|
+      obj.type = hash['type']
+      obj.id = hash['id']
+      if hash['attributes']
+        hash['attributes'].each do |key, value|
+          set_key(obj, key, value, original_keys)
+        end
+      end
+    end
+  end
+
   def self.generate_object(ruby_name, superclass, container)
     klass = Class.new(superclass)
     container.const_set(ruby_name, klass)
diff --git a/spec/json-api-vanilla/diff_spec.rb b/spec/json-api-vanilla/diff_spec.rb
index 064d837..2ca599d 100644
--- a/spec/json-api-vanilla/diff_spec.rb
+++ b/spec/json-api-vanilla/diff_spec.rb
@@ -20,6 +20,14 @@
     expect(doc.links[doc.data]['self']).to eql("http://example.com/articles")
   end
 
+  it "should read objects that are only in relationships of included" do
+    expect(doc.data.first.comments.first.post.id).to eql("42")
+  end
+
+  it "should read objects that are only in relationships of included when it is an array" do
+    expect(doc.data.first.comments.first.tags[0].id).to eql("42")
+  end
+
   it "should find objects by type and id" do
     expect(doc.find('comments', '5').body).to eql("First!")
   end
@@ -114,4 +122,24 @@ class TestClasses
       end
     end
   end
+
+  describe '.prepare_object' do
+    let(:data) do
+      {
+        'type' => 'example',
+        'id' => '1',
+        'attributes' => {
+          'name' => 'example name'
+        }
+      }
+    end
+    let(:klass) { described_class.prepare_class(data, Class.new, Module.new) }
+    subject { described_class.prepare_object(data, klass) }
+
+    it 'creates an object with the attributes mapped' do
+      expect(subject.type).to eql(data['type'])
+      expect(subject.id).to eql(data['id'])
+      expect(subject.name).to eql(data['attributes']['name'])
+    end
+  end
 end
diff --git a/spec/json-api-vanilla/example.json b/spec/json-api-vanilla/example.json
index 43550cd..0947c95 100644
--- a/spec/json-api-vanilla/example.json
+++ b/spec/json-api-vanilla/example.json
@@ -56,6 +56,17 @@
     "relationships": {
       "author": {
         "data": { "type": "people", "id": "2" }
+      },
+      "tags": {
+        "data": [
+          { "type": "tag", "id": "42" }
+        ]
+      },
+      "post": {
+        "data": {
+          "type": "post",
+          "id": "42"
+        }
       }
     },
     "links": {