diff --git a/CHANGELOG.md b/CHANGELOG.md
index 995369d..d5b84cf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,10 @@
   mixed type.
 * refactor: Remove deprecated facade.
 * feat: Add `CopyTransformer` to handle mixed to mixed mapping.
+* feat: `TraversableToTraversableTransformer` now gives a `Countable` result
+  if the source is `Countable`.
+* revert: Revert support for `Generator` target type. Impossible to have a
+  `Countable` result.
 
 ## 0.5.3
 
diff --git a/src/Model/TraversableCountableWrapper.php b/src/Model/TraversableCountableWrapper.php
new file mode 100644
index 0000000..441ab68
--- /dev/null
+++ b/src/Model/TraversableCountableWrapper.php
@@ -0,0 +1,45 @@
+<?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\Model;
+
+/**
+ * @template TKey
+ * @template TValue
+ * @implements \IteratorAggregate<TKey,TValue>
+ */
+final class TraversableCountableWrapper implements \IteratorAggregate, \Countable
+{
+    /**
+     * @param \Traversable<TKey,TValue> $traversable
+     */
+    public function __construct(
+        private \Traversable $traversable,
+        private \Countable|int $countable,
+    ) {
+    }
+
+    public function getIterator(): \Traversable
+    {
+        return $this->traversable;
+    }
+
+    public function count(): int
+    {
+        if (is_int($this->countable)) {
+            return $this->countable;
+        }
+
+        return $this->countable->count();
+    }
+}
diff --git a/src/Transformer/TraversableToTraversableTransformer.php b/src/Transformer/TraversableToTraversableTransformer.php
index 163aec7..464fc89 100644
--- a/src/Transformer/TraversableToTraversableTransformer.php
+++ b/src/Transformer/TraversableToTraversableTransformer.php
@@ -22,6 +22,7 @@
 use Rekalogika\Mapper\Exception\MissingMemberKeyTypeException;
 use Rekalogika\Mapper\Exception\MissingMemberValueTypeException;
 use Rekalogika\Mapper\MainTransformer;
+use Rekalogika\Mapper\Model\TraversableCountableWrapper;
 use Rekalogika\Mapper\ObjectCache\ObjectCache;
 use Rekalogika\Mapper\ObjectCache\ObjectCacheFactoryInterface;
 use Rekalogika\Mapper\Util\TypeCheck;
@@ -158,6 +159,12 @@ public function transform(
             }
         })();
 
+        if ($source instanceof \Countable) {
+            $target = new TraversableCountableWrapper($target, $source);
+        } elseif (is_array($source)) {
+            $target = new TraversableCountableWrapper($target, count($source));
+        }
+
         $objectCache->saveTarget($source, $targetType, $target);
 
         return $target;
@@ -171,7 +178,6 @@ public function getSupportedTransformation(): iterable
         ];
 
         $targetTypes = [
-            TypeFactory::objectOfClass(\Generator::class),
             TypeFactory::objectOfClass(\Traversable::class),
         ];
 
diff --git a/tests/Fixtures/ArrayLike/LazyDoctrineCollectionWithPresetCountable.php b/tests/Fixtures/ArrayLike/LazyDoctrineCollectionWithPresetCountable.php
new file mode 100644
index 0000000..8cb1001
--- /dev/null
+++ b/tests/Fixtures/ArrayLike/LazyDoctrineCollectionWithPresetCountable.php
@@ -0,0 +1,32 @@
+<?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\ArrayLike;
+
+use Doctrine\Common\Collections\AbstractLazyCollection;
+
+/**
+ * @extends AbstractLazyCollection<array-key,mixed>
+ */
+class LazyDoctrineCollectionWithPresetCountable extends AbstractLazyCollection
+{
+    protected function doInitialize()
+    {
+        throw new \LogicException("Not expected to be initialized");
+    }
+
+    public function count(): int
+    {
+        return 31337;
+    }
+}
diff --git a/tests/Fixtures/ArrayLike/ObjectWithLazyDoctrineCollectionWithPresetCountableProperty.php b/tests/Fixtures/ArrayLike/ObjectWithLazyDoctrineCollectionWithPresetCountableProperty.php
new file mode 100644
index 0000000..b038ead
--- /dev/null
+++ b/tests/Fixtures/ArrayLike/ObjectWithLazyDoctrineCollectionWithPresetCountableProperty.php
@@ -0,0 +1,24 @@
+<?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\ArrayLike;
+
+class ObjectWithLazyDoctrineCollectionWithPresetCountableProperty
+{
+    public LazyDoctrineCollectionWithPresetCountable $property;
+
+    public function __construct()
+    {
+        $this->property = new LazyDoctrineCollectionWithPresetCountable();
+    }
+}
diff --git a/tests/IntegrationTest/TraversableToTraversableMappingTest.php b/tests/IntegrationTest/TraversableToTraversableMappingTest.php
index e9d4fcb..dac8476 100644
--- a/tests/IntegrationTest/TraversableToTraversableMappingTest.php
+++ b/tests/IntegrationTest/TraversableToTraversableMappingTest.php
@@ -13,9 +13,11 @@
 
 namespace Rekalogika\Mapper\Tests\IntegrationTest;
 
+use Rekalogika\Mapper\Model\TraversableCountableWrapper;
 use Rekalogika\Mapper\Tests\Common\AbstractIntegrationTest;
 use Rekalogika\Mapper\Tests\Fixtures\ArrayLike\ObjectWithArrayProperty;
 use Rekalogika\Mapper\Tests\Fixtures\ArrayLike\ObjectWithLazyDoctrineCollectionProperty;
+use Rekalogika\Mapper\Tests\Fixtures\ArrayLike\ObjectWithLazyDoctrineCollectionWithPresetCountableProperty;
 use Rekalogika\Mapper\Tests\Fixtures\ArrayLike\ObjectWithTraversableProperties;
 use Rekalogika\Mapper\Tests\Fixtures\ArrayLikeDto\ObjectWithTraversablePropertyDto;
 use Rekalogika\Mapper\Tests\Fixtures\Scalar\ObjectWithScalarPropertiesDto;
@@ -54,7 +56,7 @@ public function testArrayToTraversableDto(): void
 
         $this->assertInstanceOf(ObjectWithTraversablePropertyDto::class, $result);
         $this->assertNotNull($result->property);
-        $this->assertInstanceOf(\Generator::class, $result->property);
+        $this->assertInstanceOf(TraversableCountableWrapper::class, $result->property);
 
         foreach ($result->property as $item) {
             $this->assertInstanceOf(ObjectWithScalarPropertiesDto::class, $item);
@@ -74,7 +76,23 @@ public function testLazy(): void
 
         $this->assertInstanceOf(ObjectWithTraversablePropertyDto::class, $result);
         $this->assertNotNull($result->property);
-        $this->assertInstanceOf(\Generator::class, $result->property);
+        $this->assertInstanceOf(TraversableCountableWrapper::class, $result->property);
+
+        $this->expectException(\LogicException::class);
+        foreach ($result->property as $item);
+    }
+
+    public function testExtraLazy(): void
+    {
+        $source = new ObjectWithLazyDoctrineCollectionWithPresetCountableProperty();
+
+        $result = $this->mapper->map($source, ObjectWithTraversablePropertyDto::class);
+
+        $this->assertInstanceOf(ObjectWithTraversablePropertyDto::class, $result);
+        $this->assertNotNull($result->property);
+        $this->assertInstanceOf(TraversableCountableWrapper::class, $result->property);
+
+        $this->assertEquals(31337, $result->property->count());
 
         $this->expectException(\LogicException::class);
         foreach ($result->property as $item);