diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae340d5..59aeab1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## 1.2.1
+
+* test: add tests for mapping to objects with existing value
+
 ## 1.2.0
 
 * feat: add `IterableMapperInterface` for mapping iterables
diff --git a/tests/Fixtures/ObjectWithExistingValue/FurtherInnerObject.php b/tests/Fixtures/ObjectWithExistingValue/FurtherInnerObject.php
new file mode 100644
index 0000000..c396420
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValue/FurtherInnerObject.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValue;
+
+final class FurtherInnerObject
+{
+    private ?string $property = null;
+
+    public function getProperty(): ?string
+    {
+        return $this->property;
+    }
+
+    public function setProperty(?string $property): self
+    {
+        $this->property = $property;
+
+        return $this;
+    }
+}
diff --git a/tests/Fixtures/ObjectWithExistingValue/InnerObject.php b/tests/Fixtures/ObjectWithExistingValue/InnerObject.php
new file mode 100644
index 0000000..2365225
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValue/InnerObject.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValue;
+
+final class InnerObject
+{
+    private ?string $property = null;
+    private FurtherInnerObject $furtherInnerObject;
+
+    public function __construct()
+    {
+        $this->furtherInnerObject = new FurtherInnerObject();
+    }
+
+    public function getProperty(): ?string
+    {
+        return $this->property;
+    }
+
+    public function setProperty(?string $property): self
+    {
+        $this->property = $property;
+
+        return $this;
+    }
+
+    public function getFurtherInnerObject(): FurtherInnerObject
+    {
+        return $this->furtherInnerObject;
+    }
+
+    public function setFurtherInnerObject(FurtherInnerObject $furtherInnerObject): self
+    {
+        $this->furtherInnerObject = $furtherInnerObject;
+
+        return $this;
+    }
+}
diff --git a/tests/Fixtures/ObjectWithExistingValue/RootObject.php b/tests/Fixtures/ObjectWithExistingValue/RootObject.php
new file mode 100644
index 0000000..493638b
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValue/RootObject.php
@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValue;
+
+final class RootObject
+{
+    private string $id = '_';
+    private InnerObject $innerObject;
+
+    public function __construct()
+    {
+        $this->innerObject = new InnerObject();
+    }
+
+    public function getInnerObject(): InnerObject
+    {
+        return $this->innerObject;
+    }
+
+    public function setInnerObject(InnerObject $innerObject): self
+    {
+        $this->innerObject = $innerObject;
+
+        return $this;
+    }
+
+    public function getId(): string
+    {
+        return $this->id;
+    }
+
+    public function setId(string $id): self
+    {
+        $this->id = $id;
+
+        return $this;
+    }
+}
diff --git a/tests/Fixtures/ObjectWithExistingValueDto/FurtherInnerObjectDto.php b/tests/Fixtures/ObjectWithExistingValueDto/FurtherInnerObjectDto.php
new file mode 100644
index 0000000..3274dbe
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValueDto/FurtherInnerObjectDto.php
@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto;
+
+final class FurtherInnerObjectDto
+{
+    public ?string $property = null;
+}
diff --git a/tests/Fixtures/ObjectWithExistingValueDto/InnerObjectDto.php b/tests/Fixtures/ObjectWithExistingValueDto/InnerObjectDto.php
new file mode 100644
index 0000000..019792f
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValueDto/InnerObjectDto.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto;
+
+final class InnerObjectDto
+{
+    public ?string $property = null;
+    public ?FurtherInnerObjectDto $furtherInnerObject = null;
+}
diff --git a/tests/Fixtures/ObjectWithExistingValueDto/RootObjectDto.php b/tests/Fixtures/ObjectWithExistingValueDto/RootObjectDto.php
new file mode 100644
index 0000000..061d241
--- /dev/null
+++ b/tests/Fixtures/ObjectWithExistingValueDto/RootObjectDto.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto;
+
+final class RootObjectDto
+{
+    public ?string $id = null;
+    public ?InnerObjectDto $innerObject = null;
+}
diff --git a/tests/IntegrationTest/ObjectWithExistingValueTest.php b/tests/IntegrationTest/ObjectWithExistingValueTest.php
new file mode 100644
index 0000000..85f774a
--- /dev/null
+++ b/tests/IntegrationTest/ObjectWithExistingValueTest.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Tests\IntegrationTest;
+
+use Rekalogika\Mapper\Tests\Common\FrameworkTestCase;
+use Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValue\RootObject;
+use Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto\FurtherInnerObjectDto;
+use Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto\InnerObjectDto;
+use Rekalogika\Mapper\Tests\Fixtures\ObjectWithExistingValueDto\RootObjectDto;
+
+class ObjectWithExistingValueTest extends FrameworkTestCase
+{
+    public function testObjectWithExistingValueDtoToObject(): void
+    {
+        $dto = new RootObjectDto();
+        $dto->id = 'id';
+        $dto->innerObject = new InnerObjectDto();
+        $dto->innerObject->property = 'foo';
+        $dto->innerObject->furtherInnerObject = new FurtherInnerObjectDto();
+        $dto->innerObject->furtherInnerObject->property = 'bar';
+
+        $object = $this->mapper->map($dto, RootObject::class);
+
+        $this->assertSame('id', $object->getId());
+        $this->assertSame('foo', $object->getInnerObject()->getProperty());
+        $this->assertSame('bar', $object->getInnerObject()->getFurtherInnerObject()->getProperty());
+    }
+
+    public function testObjectWithExistingValueDtoToObjectPreinitialized(): void
+    {
+        $dto = new RootObjectDto();
+        $dto->id = 'id';
+        $dto->innerObject = new InnerObjectDto();
+        $dto->innerObject->property = 'foo';
+        $dto->innerObject->furtherInnerObject = new FurtherInnerObjectDto();
+        $dto->innerObject->furtherInnerObject->property = 'bar';
+
+        $object = new RootObject();
+
+        $this->mapper->map($dto, $object);
+
+        $this->assertSame('id', $object->getId());
+        $this->assertSame('foo', $object->getInnerObject()->getProperty());
+        $this->assertSame('bar', $object->getInnerObject()->getFurtherInnerObject()->getProperty());
+    }
+}