diff --git a/src/Model/Common/AbstractJsonDeserializeObject.php b/src/Model/Common/AbstractJsonDeserializeObject.php
index 35092fa1a9..80854fd005 100644
--- a/src/Model/Common/AbstractJsonDeserializeObject.php
+++ b/src/Model/Common/AbstractJsonDeserializeObject.php
@@ -182,7 +182,19 @@ protected function getRaw($field, $default = null)
      */
     public function jsonSerialize()
     {
-        return $this->toArray();
+        return $this->toJson();
+    }
+
+    /**
+     * @return array
+     */
+    protected function toJson()
+    {
+        $data = array_filter($this->typeData, function ($value) {
+            return !is_null($value);
+        });
+
+        return $data;
     }
 
     /**
diff --git a/src/Model/Common/Money.php b/src/Model/Common/Money.php
index 97d14607be..dcf5183659 100644
--- a/src/Model/Common/Money.php
+++ b/src/Model/Common/Money.php
@@ -28,7 +28,7 @@ public function fieldDefinitions()
     }
 
     /**
-     * @return mixed
+     * @return string
      */
     public function __toString()
     {
diff --git a/src/Model/Common/PriceDraft.php b/src/Model/Common/PriceDraft.php
index 593d3f1345..85fbf3dd15 100644
--- a/src/Model/Common/PriceDraft.php
+++ b/src/Model/Common/PriceDraft.php
@@ -60,7 +60,7 @@ public function fieldDefinitions()
     /**
      * @param Money $money
      * @param Context|callable $context
-     * @return Price
+     * @return PriceDraft
      */
     public static function ofMoney(Money $money, $context = null)
     {
@@ -68,6 +68,9 @@ public static function ofMoney(Money $money, $context = null)
         return $price->setValue($money);
     }
 
+    /**
+     * @return string
+     */
     public function __toString()
     {
         return $this->getValue()->__toString();
diff --git a/src/Model/Common/Reference.php b/src/Model/Common/Reference.php
index cde1f77cf4..e73b72bcb6 100644
--- a/src/Model/Common/Reference.php
+++ b/src/Model/Common/Reference.php
@@ -31,12 +31,4 @@ public function fieldDefinitions()
 
         return $fieldDefinitions;
     }
-
-    public function jsonSerialize()
-    {
-        $data = parent::jsonSerialize();
-        unset($data['obj']);
-
-        return $data;
-    }
 }
diff --git a/tests/unit/Model/Common/ReferenceTest.php b/tests/unit/Model/Common/ReferenceTest.php
index 400f604524..948951b620 100644
--- a/tests/unit/Model/Common/ReferenceTest.php
+++ b/tests/unit/Model/Common/ReferenceTest.php
@@ -7,6 +7,7 @@
 namespace Commercetools\Core\Model\Type;
 
 use Commercetools\Core\Model\Common\Reference;
+use Commercetools\Core\Model\Product\Product;
 use Commercetools\Core\Model\ProductType\ProductType;
 use Commercetools\Core\Model\ProductType\ProductTypeReference;
 
@@ -45,4 +46,15 @@ public function testJsonSerialize()
 
         $this->assertJsonStringEqualsJsonString('{"typeId": "product-type", "id": "123456"}', json_encode($reference));
     }
+
+    public function testEmbeddedReferenceSerialize()
+    {
+        $type = ProductType::of()->setId('123456');
+        $object = Product::of()->setProductType($type->getReference());
+
+        $this->assertJsonStringEqualsJsonString(
+            '{"productType": {"typeId": "product-type", "id": "123456"}}',
+            json_encode($object)
+        );
+    }
 }