diff --git a/docs/UPGRADE-3.0.md b/docs/UPGRADE-3.0.md
index 8c92e3b..f12edb9 100644
--- a/docs/UPGRADE-3.0.md
+++ b/docs/UPGRADE-3.0.md
@@ -153,6 +153,35 @@ receive now contains the hydrator under the key `Hydrator::HYDRATOR`. Don't use
 the key `hydrator` for your own context values. If you serialize, log or compare
 the context, leave this key out.
 
+### Object to populate
+
+If you hydrate an existing object with `Hydrator::OBJECT_TO_POPULATE`, missing
+fields no longer reset promoted properties to their default value, the object
+keeps its current value. If you relied on the reset, pass the default value in
+the data.
+
+before:
+
+```php
+use Patchlevel\Hydrator\Hydrator;
+
+$profile = new Profile('patchlevel', Role::Admin);
+
+$hydrator->hydrate(Profile::class, ['name' => 'hydrator'], [Hydrator::OBJECT_TO_POPULATE => $profile]);
+
+// $profile->role is Role::Member, the default value of the promoted property
+```
+after:
+
+```php
+use Patchlevel\Hydrator\Hydrator;
+
+$profile = new Profile('patchlevel', Role::Admin);
+
+$hydrator->hydrate(Profile::class, ['name' => 'hydrator'], [Hydrator::OBJECT_TO_POPULATE => $profile]);
+
+// $profile->role is still Role::Admin
+```
 ### Wrapping a hydrator
 
 If you wrap the hydrator in your own `Hydrator` implementation, add it to the
diff --git a/docs/hydrator.md b/docs/hydrator.md
index 4ef2e7d..3720993 100644
--- a/docs/hydrator.md
+++ b/docs/hydrator.md
@@ -106,6 +106,10 @@ $profile = $hydrator->hydrate(
     [Hydrator::OBJECT_TO_POPULATE => $profile],
 );
 ```
+Only the fields in the data are set. Properties whose fields are missing keep
+their current value, promoted properties are not reset to their default value
+either. Defaults are only used for new objects.
+
 ## Rename fields
 
 By default, the property name is used to name the field in the extracted
diff --git a/src/Extension/Generated/ClassPlan.php b/src/Extension/Generated/ClassPlan.php
index 5177fa4..2286a5d 100644
--- a/src/Extension/Generated/ClassPlan.php
+++ b/src/Extension/Generated/ClassPlan.php
@@ -44,6 +44,18 @@ public function leaf(): bool
         return true;
     }
 
+    /** Whether missing fields of new objects fall back to the default of a promoted property. */
+    public function defaults(): bool
+    {
+        foreach ($this->properties as $property) {
+            if ($property->hasDefault()) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     /** @return array<int, NestedPlan> slot => nested class whose objects may be mapped in place */
     public function nested(): array
     {
diff --git a/src/Extension/Generated/CodeEmitter.php b/src/Extension/Generated/CodeEmitter.php
index c745273..f04660a 100644
--- a/src/Extension/Generated/CodeEmitter.php
+++ b/src/Extension/Generated/CodeEmitter.php
@@ -78,10 +78,11 @@ public function emit(string $namespace, string $className): string
             $this->properties[] = sprintf('public NestedMapper $x%d;', $slot);
         }
 
-        [$hydrate, $hydrateHelpers] = $this->hydrateBody();
+        [$hydrate, $hydrateHelpers] = $this->hydrateBody(true);
+        [$populate, $populateHelpers] = $plan->defaults() ? $this->hydrateBody(false) : ['', []];
         [$extract, $extractHelpers] = $this->extractBody();
 
-        foreach ([...$hydrateHelpers, ...$extractHelpers] as $helper) {
+        foreach ([...$hydrateHelpers, ...$populateHelpers, ...$extractHelpers] as $helper) {
             $initialize[] = $helper;
         }
 
@@ -95,6 +96,18 @@ public function emit(string $namespace, string $className): string
                 'class' => $plan->className(),
             ]);
             $hydrate = 'return ($this->h)($object, $data, $context, $inline);';
+
+            if ($populate !== '') {
+                $this->properties[] = 'public Closure $p;';
+                $initialize[] = Templates::render(Templates::CLOSURE, [
+                    'slot' => 'p',
+                    'signature' => 'object $object, array $data, array $context, bool $inline',
+                    'return' => 'object',
+                    'body' => $populate,
+                    'class' => $plan->className(),
+                ]);
+                $populate = 'return ($this->p)($object, $data, $context, $inline);';
+            }
         }
 
         if ($plan->scopedExtract) {
@@ -122,6 +135,11 @@ public function emit(string $namespace, string $className): string
             'properties' => implode("\n", $this->properties),
             // nested objects are only mapped right away for calls of the hydrator which created the mapper
             'hydrate' => self::withInline($hydrate, $plan->nested() === [] ? 'false' : Templates::OWNER),
+            // existing objects keep the values of missing fields, only classes with promoted defaults need own code
+            'populateCall' => $populate === '' ? '' : Templates::POPULATE_CALL,
+            'populate' => $populate === '' ? '' : Templates::render(Templates::POPULATE, [
+                'body' => self::withInline($populate, $plan->nested() === [] ? 'false' : Templates::OWNER),
+            ]),
             'extract' => self::withInline($extract, $plan->nested() === [] ? 'false' : Templates::OWNER),
             // the nested entry points are only called by a parent mapper which already did these checks
             'hydrateNested' => self::withInline($hydrate, 'true'),
@@ -131,7 +149,7 @@ public function emit(string $namespace, string $className): string
         ]);
 
         // empty placeholders leave blank lines behind
-        $code = preg_replace(["/\n{3,}/", "/{\n\n/"], ["\n\n", "{\n"], $code);
+        $code = preg_replace(["/\n{3,}/", "/{\n\n/", "/\n\n([ \t]*})/"], ["\n\n", "{\n", "\n$1"], $code);
         assert($code !== null);
 
         return $code;
@@ -180,21 +198,23 @@ private function recursive(): string
     /**
      * Generates the hydrate code, properties which need another scope are assigned in a helper closure.
      *
+     * @param bool $defaults whether missing fields fall back to the default of a promoted property, only for new objects
+     *
      * @return array{string, list<string>} body and init code of the helper closures
      */
-    private function hydrateBody(): array
+    private function hydrateBody(bool $defaults): array
     {
         $main = [];
         $scoped = [];
 
         foreach ($this->plan->properties as $property) {
             if ($property->hydrateScope !== null) {
-                $scoped[$property->hydrateScope][] = $this->assignment($property);
+                $scoped[$property->hydrateScope][] = $this->assignment($property, $defaults);
 
                 continue;
             }
 
-            $main[] = $this->assignment($property);
+            $main[] = $this->assignment($property, $defaults);
         }
 
         $helpers = [];
@@ -215,9 +235,9 @@ private function hydrateBody(): array
         return [implode("\n\n", $main), $helpers];
     }
 
-    private function assignment(PropertyPlan $property): string
+    private function assignment(PropertyPlan $property, bool $defaults): string
     {
-        $template = $property->hasDefault() ? Templates::ASSIGN_DEFAULT : Templates::ASSIGN;
+        $template = $defaults && $property->hasDefault() ? Templates::ASSIGN_DEFAULT : Templates::ASSIGN;
         $code = [];
 
         // the first alias in the data takes the place of the missing field
diff --git a/src/Extension/Generated/MapperFiles.php b/src/Extension/Generated/MapperFiles.php
index 3fb9034..6fc6ac0 100644
--- a/src/Extension/Generated/MapperFiles.php
+++ b/src/Extension/Generated/MapperFiles.php
@@ -24,7 +24,7 @@ final class MapperFiles
     public const NAMESPACE = 'Patchlevel\\Hydrator\\Generated';
 
     /** Part of the name, bump it whenever the generated code changes. */
-    public const VERSION = 11;
+    public const VERSION = 12;
 
     public function __construct(
         public readonly string $cachePath,
diff --git a/src/Extension/Generated/Templates.php b/src/Extension/Generated/Templates.php
index c0317c3..e4b3bd2 100644
--- a/src/Extension/Generated/Templates.php
+++ b/src/Extension/Generated/Templates.php
@@ -98,6 +98,7 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+            {{populateCall}}
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -126,6 +127,8 @@ public function extractNested(object $object, array $context): array
         {{extractNested}}
     }
 
+    {{populate}}
+
     protected function initialize(): void
     {
         {{initialize}}
@@ -137,6 +140,19 @@ protected function mayReachItself(): bool
     }
 }
 
+PHP;
+
+    public const POPULATE_CALL = <<<'PHP'
+
+return $this->populate($object, $data, $context);
+PHP;
+
+    /** Existing objects keep the values of missing fields, the defaults of promoted properties are only set for new objects. */
+    public const POPULATE = <<<'PHP'
+private function populate(object $object, array $data, array $context): object
+{
+    {{body}}
+}
 PHP;
 
     public const CLOSURE = <<<'PHP'
diff --git a/src/Mapper/ReflectionMapper.php b/src/Mapper/ReflectionMapper.php
index babcd1c..0468034 100644
--- a/src/Mapper/ReflectionMapper.php
+++ b/src/Mapper/ReflectionMapper.php
@@ -60,17 +60,15 @@ public function __construct(
      */
     public function hydrate(array $data, array $context): object
     {
-        $metadata = $this->metadata;
-
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             // only unset if it is there, unset() copies the context even if the key does not exist
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
-        } else {
-            $object = $metadata->newInstance();
+
+            return $this->hydrateProperties($object, $data, $context, $this->nested($context), true);
         }
 
-        return $this->hydrateProperties($object, $data, $context, $this->nested($context));
+        return $this->hydrateProperties($this->metadata->newInstance(), $data, $context, $this->nested($context));
     }
 
     /**
@@ -78,10 +76,11 @@ public function hydrate(array $data, array $context): object
      * @param array<string, mixed>                     $data
      * @param array<string, mixed>                     $context
      * @param array<string, array{class-string, bool}> $nested
+     * @param bool                                     $populate the object already exists, it keeps the values of missing fields
      *
      * @return T
      */
-    private function hydrateProperties(object $object, array $data, array $context, array $nested): object
+    private function hydrateProperties(object $object, array $data, array $context, array $nested, bool $populate = false): object
     {
         $metadata = $this->metadata;
         $constructorParameters = null;
@@ -91,7 +90,7 @@ private function hydrateProperties(object $object, array $data, array $context,
                 $alias = self::alias($propertyMetadata, $data);
 
                 if ($alias === null) {
-                    if (!$propertyMetadata->reflection->isPromoted()) {
+                    if ($populate || !$propertyMetadata->reflection->isPromoted()) {
                         continue;
                     }
 
diff --git a/tests/Unit/Extension/Generated/GeneratedStackHydratorTest.php b/tests/Unit/Extension/Generated/GeneratedStackHydratorTest.php
index f76a6f1..138fcfe 100644
--- a/tests/Unit/Extension/Generated/GeneratedStackHydratorTest.php
+++ b/tests/Unit/Extension/Generated/GeneratedStackHydratorTest.php
@@ -60,6 +60,7 @@
 use Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto;
 use Patchlevel\Hydrator\Tests\Unit\Fixture\ParentDto;
 use Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateChildDto;
+use Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto;
 use Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto;
 use Patchlevel\Hydrator\Tests\Unit\Fixture\ProfileCreated;
 use Patchlevel\Hydrator\Tests\Unit\Fixture\ProfileCreatedWithInlineNormalizer;
@@ -126,6 +127,7 @@ final class GeneratedStackHydratorTest extends TestCase
         ProfileCreatedWithInlineNormalizer::class,
         PrivatePropertiesDto::class,
         PrivateChildDto::class,
+        PrivateDefaultChildDto::class,
         SensitiveDataProfileCreated::class,
         NestedLifecycleDto::class,
         AliasDto::class,
@@ -509,6 +511,73 @@ public function testExtractWithAlias(): void
         );
     }
 
+    public function testHydrateWithObjectToPopulateAndAlias(): void
+    {
+        $dto = new AliasDto(Email::fromString('old@patchlevel.de'), 'old');
+
+        $object = $this->hydrator->hydrate(
+            AliasDto::class,
+            ['username' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        self::assertSame($dto, $object);
+        self::assertSame('new', $dto->name);
+        self::assertEquals(Email::fromString('old@patchlevel.de'), $dto->email);
+    }
+
+    public function testHydrateWithObjectToPopulateKeepsMissingFields(): void
+    {
+        $dto = new DefaultDto('old', Email::fromString('old@patchlevel.de'));
+        $dto->admin = false;
+
+        $object = $this->hydrator->hydrate(
+            DefaultDto::class,
+            ['name' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        // missing fields keep the values of the object, also promoted properties with a default
+        self::assertSame($dto, $object);
+        self::assertSame('new', $dto->name);
+        self::assertEquals(Email::fromString('old@patchlevel.de'), $dto->email);
+        self::assertFalse($dto->admin);
+    }
+
+    public function testHydrateWithObjectToPopulateKeepsMissingPrivateFields(): void
+    {
+        $dto = new PrivatePropertiesDto(ProfileId::fromString('1'), 'old', 30);
+
+        $object = $this->hydrator->hydrate(
+            PrivatePropertiesDto::class,
+            ['name' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        self::assertSame($dto, $object);
+        self::assertSame('1', $dto->profileId()->toString());
+        self::assertSame('new', $dto->name());
+        self::assertSame(30, $dto->age());
+    }
+
+    public function testHydrateWithObjectToPopulateKeepsMissingPrivateFieldsOfParent(): void
+    {
+        $dto = new PrivateDefaultChildDto('kept');
+
+        $object = $this->hydrator->hydrate(
+            PrivateDefaultChildDto::class,
+            ['name' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        self::assertSame($dto, $object);
+        self::assertSame('new', $dto->name);
+        self::assertSame('kept', $dto->note());
+
+        // new objects still fall back to the default
+        self::assertSame('default', $this->hydrator->hydrate(PrivateDefaultChildDto::class, [])->note());
+    }
+
     public function testHydrateWithTypeMismatch(): void
     {
         $this->expectException(TypeMismatch::class);
diff --git a/tests/Unit/Extension/Generated/Snapshot/AliasDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/AliasDtoMapper.php
index 3b7221d..f6c362f 100644
--- a/tests/Unit/Extension/Generated/Snapshot/AliasDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/AliasDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -41,6 +41,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -227,6 +229,47 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        if (!\array_key_exists('email', $data) && \array_key_exists('mail', $data)) {
+            $data['email'] = $data['mail'];
+        }
+
+        if (!\array_key_exists('email', $data) && \array_key_exists('e_mail', $data)) {
+            $data['email'] = $data['e_mail'];
+        }
+
+        if (\array_key_exists('email', $data)) {
+            try {
+                $value = $this->n0->denormalize($data['email'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\AliasDto::class, 'email', $this->n0::class, $e);
+            }
+
+            try {
+                $object->email = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\AliasDto::class, 'email', $e);
+            }
+        }
+
+        if (!\array_key_exists('name', $data) && \array_key_exists('username', $data)) {
+            $data['name'] = $data['username'];
+        }
+
+        if (\array_key_exists('name', $data)) {
+            $value = $data['name'];
+
+            try {
+                $object->name = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\AliasDto::class, 'name', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('email');
diff --git a/tests/Unit/Extension/Generated/Snapshot/Circle1DtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/Circle1DtoMapper.php
index edcac33..f7991a1 100644
--- a/tests/Unit/Extension/Generated/Snapshot/Circle1DtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/Circle1DtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/Circle2DtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/Circle2DtoMapper.php
index ccb0f9f..6671bbd 100644
--- a/tests/Unit/Extension/Generated/Snapshot/Circle2DtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/Circle2DtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/Circle3DtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/Circle3DtoMapper.php
index d62ad60..7db3c06 100644
--- a/tests/Unit/Extension/Generated/Snapshot/Circle3DtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/Circle3DtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/ContextAwareDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/ContextAwareDtoMapper.php
index 6de0b8f..b2727a9 100644
--- a/tests/Unit/Extension/Generated/Snapshot/ContextAwareDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/ContextAwareDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/DefaultDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/DefaultDtoMapper.php
index c8d3123..440aeba 100644
--- a/tests/Unit/Extension/Generated/Snapshot/DefaultDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/DefaultDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -44,6 +44,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -254,6 +256,53 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        $inline = ($context[Hydrator::HYDRATOR] ?? null) === $this->hydrator;
+
+        if (\array_key_exists('admin', $data)) {
+            $value = $data['admin'];
+
+            try {
+                $object->admin = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\DefaultDto::class, 'admin', $e);
+            }
+        }
+
+        if (\array_key_exists('name', $data)) {
+            $value = $data['name'];
+
+            try {
+                $object->name = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\DefaultDto::class, 'name', $e);
+            }
+        }
+
+        if (\array_key_exists('email', $data)) {
+            try {
+                $value = $data['email'];
+
+                if ($this->i0 && $inline && \is_array($value)) {
+                    $value = $this->x0->hydrateNested($value, $context);
+                } else {
+                    $value = $this->n0->denormalize($value, $context);
+                }
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\DefaultDto::class, 'email', $this->n0::class, $e);
+            }
+
+            try {
+                $object->email = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\DefaultDto::class, 'email', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->d0 = $this->promotedDefault('email');
diff --git a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerDtoMapper.php
index 505368e..acfbf13 100644
--- a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithIterablesDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithIterablesDtoMapper.php
index d18881a..c8a57d9 100644
--- a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithIterablesDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithIterablesDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -46,6 +46,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -552,6 +554,105 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        if (\array_key_exists('defaultArray', $data)) {
+            try {
+                $value = $this->n0->denormalize($data['defaultArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'defaultArray', $this->n0::class, $e);
+            }
+
+            try {
+                $object->defaultArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'defaultArray', $e);
+            }
+        }
+
+        if (\array_key_exists('listArray', $data)) {
+            try {
+                $value = $this->n1->denormalize($data['listArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'listArray', $this->n1::class, $e);
+            }
+
+            try {
+                $object->listArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'listArray', $e);
+            }
+        }
+
+        if (\array_key_exists('iterableArray', $data)) {
+            try {
+                $value = $this->n2->denormalize($data['iterableArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'iterableArray', $this->n2::class, $e);
+            }
+
+            try {
+                $object->iterableArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'iterableArray', $e);
+            }
+        }
+
+        if (\array_key_exists('hashMap', $data)) {
+            try {
+                $value = $this->n3->denormalize($data['hashMap'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'hashMap', $this->n3::class, $e);
+            }
+
+            try {
+                $object->hashMap = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'hashMap', $e);
+            }
+        }
+
+        if (\array_key_exists('nested', $data)) {
+            try {
+                $value = $this->n4->denormalize($data['nested'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'nested', $this->n4::class, $e);
+            }
+
+            try {
+                $object->nested = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'nested', $e);
+            }
+        }
+
+        if (\array_key_exists('jsonArray', $data)) {
+            $value = $data['jsonArray'];
+
+            try {
+                $object->jsonArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'jsonArray', $e);
+            }
+        }
+
+        if (\array_key_exists('shapeArray', $data)) {
+            try {
+                $value = $this->n5->denormalize($data['shapeArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'shapeArray', $this->n5::class, $e);
+            }
+
+            try {
+                $object->shapeArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithIterablesDto::class, 'shapeArray', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('defaultArray');
diff --git a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithNullableDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithNullableDtoMapper.php
index 891b8fd..f777aa6 100644
--- a/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithNullableDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/InferNormalizerWithNullableDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -45,6 +45,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -447,6 +449,81 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        if (\array_key_exists('status', $data)) {
+            try {
+                $value = $this->n0->denormalize($data['status'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'status', $this->n0::class, $e);
+            }
+
+            try {
+                $object->status = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'status', $e);
+            }
+        }
+
+        if (\array_key_exists('dateTimeImmutable', $data)) {
+            try {
+                $value = $this->n1->denormalize($data['dateTimeImmutable'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTimeImmutable', $this->n1::class, $e);
+            }
+
+            try {
+                $object->dateTimeImmutable = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTimeImmutable', $e);
+            }
+        }
+
+        if (\array_key_exists('dateTime', $data)) {
+            try {
+                $value = $this->n2->denormalize($data['dateTime'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTime', $this->n2::class, $e);
+            }
+
+            try {
+                $object->dateTime = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTime', $e);
+            }
+        }
+
+        if (\array_key_exists('dateTimeZone', $data)) {
+            try {
+                $value = $this->n3->denormalize($data['dateTimeZone'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTimeZone', $this->n3::class, $e);
+            }
+
+            try {
+                $object->dateTimeZone = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'dateTimeZone', $e);
+            }
+        }
+
+        if (\array_key_exists('profileId', $data)) {
+            try {
+                $value = $this->n4->denormalize($data['profileId'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'profileId', $this->n4::class, $e);
+            }
+
+            try {
+                $object->profileId = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\InferNormalizerWithNullableDto::class, 'profileId', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('status');
diff --git a/tests/Unit/Extension/Generated/Snapshot/LazyProfileCreatedMapper.php b/tests/Unit/Extension/Generated/Snapshot/LazyProfileCreatedMapper.php
index ff94539..3474d62 100644
--- a/tests/Unit/Extension/Generated/Snapshot/LazyProfileCreatedMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/LazyProfileCreatedMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/NestedLifecycleDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/NestedLifecycleDtoMapper.php
index b919576..3fb3ecd 100644
--- a/tests/Unit/Extension/Generated/Snapshot/NestedLifecycleDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/NestedLifecycleDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -46,6 +46,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -344,6 +346,59 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        $inline = ($context[Hydrator::HYDRATOR] ?? null) === $this->hydrator;
+
+        if (\array_key_exists('child', $data)) {
+            try {
+                $value = $data['child'];
+
+                if ($this->i0 && $inline && \is_array($value)) {
+                    $value = $this->x0->hydrateNested($value, $context);
+                } else {
+                    $value = $this->n0->denormalize($value, $context);
+                }
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NestedLifecycleDto::class, 'child', $this->n0::class, $e);
+            }
+
+            try {
+                $object->child = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NestedLifecycleDto::class, 'child', $e);
+            }
+        }
+
+        if (\array_key_exists('items', $data)) {
+            try {
+                $value = $data['items'];
+
+                if ($this->i1 && $inline && \is_array($value)) {
+                    $items = [];
+
+                    foreach ($value as $key => $item) {
+                        $items[$key] = \is_array($item) ? $this->x0->hydrateNested($item, $context) : $this->n2->denormalize($item, $context);
+                    }
+
+                    $value = $items;
+                } else {
+                    $value = $this->n1->denormalize($value, $context);
+                }
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NestedLifecycleDto::class, 'items', $this->n1::class, $e);
+            }
+
+            try {
+                $object->items = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NestedLifecycleDto::class, 'items', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('child');
diff --git a/tests/Unit/Extension/Generated/Snapshot/NormalizerInBaseClassDefinedDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/NormalizerInBaseClassDefinedDtoMapper.php
index a4a620d..bc39ee9 100644
--- a/tests/Unit/Extension/Generated/Snapshot/NormalizerInBaseClassDefinedDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/NormalizerInBaseClassDefinedDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -51,6 +51,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -645,6 +647,125 @@ public function extractNested(object $object, array $context): array
         ];
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        $inline = ($context[Hydrator::HYDRATOR] ?? null) === $this->hydrator;
+
+        if (\array_key_exists('status', $data)) {
+            try {
+                $value = $this->n0->denormalize($data['status'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'status', $this->n0::class, $e);
+            }
+
+            try {
+                $object->status = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'status', $e);
+            }
+        }
+
+        if (\array_key_exists('profileCreated', $data)) {
+            try {
+                $value = $data['profileCreated'];
+
+                if ($this->i0 && $inline && \is_array($value)) {
+                    $value = $this->x0->hydrateNested($value, $context);
+                } else {
+                    $value = $this->n1->denormalize($value, $context);
+                }
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'profileCreated', $this->n1::class, $e);
+            }
+
+            try {
+                $object->profileCreated = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'profileCreated', $e);
+            }
+        }
+
+        if (\array_key_exists('defaultArray', $data)) {
+            try {
+                $value = $this->n2->denormalize($data['defaultArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'defaultArray', $this->n2::class, $e);
+            }
+
+            try {
+                $object->defaultArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'defaultArray', $e);
+            }
+        }
+
+        if (\array_key_exists('listArray', $data)) {
+            try {
+                $value = $this->n3->denormalize($data['listArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'listArray', $this->n3::class, $e);
+            }
+
+            try {
+                $object->listArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'listArray', $e);
+            }
+        }
+
+        if (\array_key_exists('iterableArray', $data)) {
+            try {
+                $value = $this->n4->denormalize($data['iterableArray'], $context);
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'iterableArray', $this->n4::class, $e);
+            }
+
+            try {
+                $object->iterableArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'iterableArray', $e);
+            }
+        }
+
+        if (\array_key_exists('skillsHashMap', $data)) {
+            try {
+                $value = $data['skillsHashMap'];
+
+                if ($this->i1 && $inline && \is_array($value)) {
+                    $items = [];
+
+                    foreach ($value as $key => $item) {
+                        $items[$key] = \is_array($item) ? $this->x1->hydrateNested($item, $context) : $this->n6->denormalize($item, $context);
+                    }
+
+                    $value = $items;
+                } else {
+                    $value = $this->n5->denormalize($value, $context);
+                }
+            } catch (Throwable $e) {
+                throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'skillsHashMap', $this->n5::class, $e);
+            }
+
+            try {
+                $object->skillsHashMap = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'skillsHashMap', $e);
+            }
+        }
+
+        if (\array_key_exists('jsonArray', $data)) {
+            $value = $data['jsonArray'];
+
+            try {
+                $object->jsonArray = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\NormalizerInBaseClassDefinedDto::class, 'jsonArray', $e);
+            }
+        }
+
+        return $object;
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('status');
diff --git a/tests/Unit/Extension/Generated/Snapshot/ParentDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/ParentDtoMapper.php
index 5c8c3c9..51564a2 100644
--- a/tests/Unit/Extension/Generated/Snapshot/ParentDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/ParentDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/PrivateChildDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/PrivateChildDtoMapper.php
index 1e0fb37..282499c 100644
--- a/tests/Unit/Extension/Generated/Snapshot/PrivateChildDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/PrivateChildDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/PrivateDefaultChildDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/PrivateDefaultChildDtoMapper.php
new file mode 100644
index 0000000..ce748c5
--- /dev/null
+++ b/tests/Unit/Extension/Generated/Snapshot/PrivateDefaultChildDtoMapper.php
@@ -0,0 +1,172 @@
+<?php
+
+/**
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
+ *
+ * strict_types is intentionally not declared: property assignments must use the coercive
+ * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
+ */
+
+namespace Patchlevel\Hydrator\Tests\Snapshot;
+
+use Closure;
+use Patchlevel\Hydrator\CircularReference;
+use Patchlevel\Hydrator\DenormalizationFailure;
+use Patchlevel\Hydrator\Extension\Generated\GeneratedMapper;
+use Patchlevel\Hydrator\Extension\Generated\NestedMapper;
+use Patchlevel\Hydrator\Hydrator;
+use Patchlevel\Hydrator\NormalizationFailure;
+use Patchlevel\Hydrator\Normalizer\Normalizer;
+use Patchlevel\Hydrator\Normalizer\ObjectNormalizer;
+use Patchlevel\Hydrator\TypeMismatch;
+use ReflectionParameter;
+use Throwable;
+use TypeError;
+
+/**
+ * @internal
+ *
+ * Generated mapper of {@see \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto}.
+ */
+final class PrivateDefaultChildDtoMapper extends GeneratedMapper
+{
+    public Closure $hp0;
+    public Closure $hp1;
+    public Closure $ep2;
+
+    public function hydrate(array $data, array $context): object
+    {
+        if (!$this->ready) {
+            $this->init();
+        }
+
+        if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
+            $object = $context[Hydrator::OBJECT_TO_POPULATE];
+            unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
+        } else {
+            $object = $this->reflection->newInstanceWithoutConstructor();
+        }
+
+        $inline = false;
+
+        if (\array_key_exists('name', $data)) {
+            $value = $data['name'];
+
+            try {
+                $object->name = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto::class, 'name', $e);
+            }
+        }
+
+        ($this->hp0)($object, $data, $context, $inline);
+
+        return $object;
+    }
+
+    public function extract(object $object, array $context): array
+    {
+        if (!$this->ready) {
+            $this->init();
+        }
+
+        $inline = false;
+
+        [$v_note] = ($this->ep2)($object, $context, $inline);
+
+        return [
+            'name' => $object->name,
+            'note' => $v_note,
+        ];
+    }
+
+    public function hydrateNested(array $data, array $context): object
+    {
+        $object = $this->reflection->newInstanceWithoutConstructor();
+
+        $inline = true;
+
+        if (\array_key_exists('name', $data)) {
+            $value = $data['name'];
+
+            try {
+                $object->name = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto::class, 'name', $e);
+            }
+        }
+
+        ($this->hp0)($object, $data, $context, $inline);
+
+        return $object;
+    }
+
+    public function extractNested(object $object, array $context): array
+    {
+        $inline = true;
+
+        [$v_note] = ($this->ep2)($object, $context, $inline);
+
+        return [
+            'name' => $object->name,
+            'note' => $v_note,
+        ];
+    }
+
+    private function populate(object $object, array $data, array $context): object
+    {
+        $inline = false;
+
+        if (\array_key_exists('name', $data)) {
+            $value = $data['name'];
+
+            try {
+                $object->name = $value;
+            } catch (TypeError $e) {
+                throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto::class, 'name', $e);
+            }
+        }
+
+        ($this->hp1)($object, $data, $context, $inline);
+
+        return $object;
+    }
+
+    protected function initialize(): void
+    {
+        $this->hp0 = Closure::bind(function (object $object, array $data, array $context, bool $inline): void {
+            if (\array_key_exists('note', $data)) {
+                $value = $data['note'];
+
+                try {
+                    $object->note = $value;
+                } catch (TypeError $e) {
+                    throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto::class, 'note', $e);
+                }
+            } else {
+                $object->note = 'default';
+            }
+        }, $this, \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultParentDto::class);
+        $this->hp1 = Closure::bind(function (object $object, array $data, array $context, bool $inline): void {
+            if (\array_key_exists('note', $data)) {
+                $value = $data['note'];
+
+                try {
+                    $object->note = $value;
+                } catch (TypeError $e) {
+                    throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultChildDto::class, 'note', $e);
+                }
+            }
+        }, $this, \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultParentDto::class);
+        $this->ep2 = Closure::bind(function (object $object, array $context, bool $inline): array {
+            return [$object->note];
+        }, $this, \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivateDefaultParentDto::class);
+    }
+
+    protected function mayReachItself(): bool
+    {
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/tests/Unit/Extension/Generated/Snapshot/PrivatePropertiesDtoMapper.php b/tests/Unit/Extension/Generated/Snapshot/PrivatePropertiesDtoMapper.php
index 9265c88..6b875af 100644
--- a/tests/Unit/Extension/Generated/Snapshot/PrivatePropertiesDtoMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/PrivatePropertiesDtoMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
@@ -32,6 +32,7 @@ final class PrivatePropertiesDtoMapper extends GeneratedMapper
 {
     public Normalizer $n0;
     public Closure $h;
+    public Closure $p;
     public Closure $e;
 
     public function hydrate(array $data, array $context): object
@@ -43,6 +44,8 @@ public function hydrate(array $data, array $context): object
         if (isset($context[Hydrator::OBJECT_TO_POPULATE])) {
             $object = $context[Hydrator::OBJECT_TO_POPULATE];
             unset($context[Hydrator::OBJECT_TO_POPULATE]);
+
+            return $this->populate($object, $data, $context);
         } else {
             $object = $this->reflection->newInstanceWithoutConstructor();
         }
@@ -79,6 +82,13 @@ public function extractNested(object $object, array $context): array
         return ($this->e)($object, $context, $inline);
     }
 
+    private function populate(object $object, array $data, array $context): object
+    {
+        $inline = false;
+
+        return ($this->p)($object, $data, $context, $inline);
+    }
+
     protected function initialize(): void
     {
         $this->n0 = $this->normalizer('profileId');
@@ -121,6 +131,43 @@ protected function initialize(): void
 
             return $object;
         }, $this, \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class);
+        $this->p = Closure::bind(function (object $object, array $data, array $context, bool $inline): object {
+            if (\array_key_exists('profileId', $data)) {
+                try {
+                    $value = $this->n0->denormalize($data['profileId'], $context);
+                } catch (Throwable $e) {
+                    throw new DenormalizationFailure(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class, 'profileId', $this->n0::class, $e);
+                }
+
+                try {
+                    $object->profileId = $value;
+                } catch (TypeError $e) {
+                    throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class, 'profileId', $e);
+                }
+            }
+
+            if (\array_key_exists('name', $data)) {
+                $value = $data['name'];
+
+                try {
+                    $object->name = $value;
+                } catch (TypeError $e) {
+                    throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class, 'name', $e);
+                }
+            }
+
+            if (\array_key_exists('age', $data)) {
+                $value = $data['age'];
+
+                try {
+                    $object->age = $value;
+                } catch (TypeError $e) {
+                    throw new TypeMismatch(\Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class, 'age', $e);
+                }
+            }
+
+            return $object;
+        }, $this, \Patchlevel\Hydrator\Tests\Unit\Fixture\PrivatePropertiesDto::class);
         $this->e = Closure::bind(function (object $object, array $context, bool $inline): array {
             if ($this->tracked) {
                 $id = \spl_object_id($object);
diff --git a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedMapper.php b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedMapper.php
index 4302d55..23e8c32 100644
--- a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWithInlineNormalizerMapper.php b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWithInlineNormalizerMapper.php
index b8808c3..d78420f 100644
--- a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWithInlineNormalizerMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWithInlineNormalizerMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWrapperMapper.php b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWrapperMapper.php
index 0783902..ceef1cd 100644
--- a/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWrapperMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/ProfileCreatedWrapperMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/SensitiveDataProfileCreatedMapper.php b/tests/Unit/Extension/Generated/Snapshot/SensitiveDataProfileCreatedMapper.php
index ca86e82..2407c04 100644
--- a/tests/Unit/Extension/Generated/Snapshot/SensitiveDataProfileCreatedMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/SensitiveDataProfileCreatedMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Extension/Generated/Snapshot/WrongNormalizerMapper.php b/tests/Unit/Extension/Generated/Snapshot/WrongNormalizerMapper.php
index 8e0e712..5efffcd 100644
--- a/tests/Unit/Extension/Generated/Snapshot/WrongNormalizerMapper.php
+++ b/tests/Unit/Extension/Generated/Snapshot/WrongNormalizerMapper.php
@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Generated by patchlevel/hydrator (version 11). Do not edit.
+ * Generated by patchlevel/hydrator (version 12). Do not edit.
  *
  * strict_types is intentionally not declared: property assignments must use the coercive
  * typing mode, exactly like ReflectionProperty::setValue() which the ReflectionMapper uses.
diff --git a/tests/Unit/Fixture/PrivateDefaultChildDto.php b/tests/Unit/Fixture/PrivateDefaultChildDto.php
new file mode 100644
index 0000000..10c54a5
--- /dev/null
+++ b/tests/Unit/Fixture/PrivateDefaultChildDto.php
@@ -0,0 +1,10 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\Hydrator\Tests\Unit\Fixture;
+
+final class PrivateDefaultChildDto extends PrivateDefaultParentDto
+{
+    public string $name = '';
+}
diff --git a/tests/Unit/Fixture/PrivateDefaultParentDto.php b/tests/Unit/Fixture/PrivateDefaultParentDto.php
new file mode 100644
index 0000000..4aaa179
--- /dev/null
+++ b/tests/Unit/Fixture/PrivateDefaultParentDto.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Patchlevel\Hydrator\Tests\Unit\Fixture;
+
+abstract class PrivateDefaultParentDto
+{
+    public function __construct(
+        private string $note = 'default',
+    ) {
+    }
+
+    public function note(): string
+    {
+        return $this->note;
+    }
+}
diff --git a/tests/Unit/StackHydratorTest.php b/tests/Unit/StackHydratorTest.php
index 53eee9b..cceec57 100644
--- a/tests/Unit/StackHydratorTest.php
+++ b/tests/Unit/StackHydratorTest.php
@@ -374,6 +374,39 @@ public function testExtractWithAlias(): void
         );
     }
 
+    public function testHydrateWithObjectToPopulateAndAlias(): void
+    {
+        $dto = new AliasDto(Email::fromString('old@patchlevel.de'), 'old');
+
+        $object = $this->hydrator->hydrate(
+            AliasDto::class,
+            ['username' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        self::assertSame($dto, $object);
+        self::assertSame('new', $dto->name);
+        self::assertEquals(Email::fromString('old@patchlevel.de'), $dto->email);
+    }
+
+    public function testHydrateWithObjectToPopulateKeepsMissingFields(): void
+    {
+        $dto = new DefaultDto('old', Email::fromString('old@patchlevel.de'));
+        $dto->admin = false;
+
+        $object = $this->hydrator->hydrate(
+            DefaultDto::class,
+            ['name' => 'new'],
+            [Hydrator::OBJECT_TO_POPULATE => $dto],
+        );
+
+        // missing fields keep the values of the object, also promoted properties with a default
+        self::assertSame($dto, $object);
+        self::assertSame('new', $dto->name);
+        self::assertEquals(Email::fromString('old@patchlevel.de'), $dto->email);
+        self::assertFalse($dto->admin);
+    }
+
     public function testHydrateWithTypeMismatch(): void
     {
         $this->expectException(TypeMismatch::class);