diff --git a/lib/FieldType/DataTransformer/DateTimeValueTransformer.php b/lib/FieldType/DataTransformer/DateTimeValueTransformer.php
index 50cb9df8f..d25462a44 100644
--- a/lib/FieldType/DataTransformer/DateTimeValueTransformer.php
+++ b/lib/FieldType/DataTransformer/DateTimeValueTransformer.php
@@ -9,9 +9,9 @@
  */
 namespace EzSystems\RepositoryForms\FieldType\DataTransformer;
 
-use DateTime;
 use eZ\Publish\Core\FieldType\DateAndTime\Value;
 use Symfony\Component\Form\DataTransformerInterface;
+use Symfony\Component\Form\Exception\TransformationFailedException;
 
 /**
  * DataTransformer for DateAndTime\Value.
@@ -21,28 +21,48 @@ class DateTimeValueTransformer implements DataTransformerInterface
     /**
      * @param mixed $value
      *
-     * @return DateTime|null
+     * @return int|null
+     *
+     * @throws TransformationFailedException
      */
     public function transform($value)
     {
+        if (null === $value) {
+            return null;
+        }
+
         if (!$value instanceof Value) {
+            throw new TransformationFailedException(
+                sprintf('Expected a %s, got %s instead', Value::class, gettype($value))
+            );
+        }
+
+        if (null === $value->value) {
             return null;
         }
 
-        return $value->value;
+        return $value->value->getTimestamp();
     }
 
     /**
      * @param mixed $value
      *
      * @return Value|null
+     *
+     * @throws TransformationFailedException
      */
     public function reverseTransform($value)
     {
-        if ($value === null || !$value instanceof DateTime) {
+        if (empty($value)) {
             return null;
         }
 
-        return new Value($value);
+        if (!is_numeric($value)) {
+            throw new TransformationFailedException(
+                sprintf('Expected a numeric, got %s instead', gettype($value))
+            );
+        }
+
+        return Value::fromTimestamp($value);
     }
 }
diff --git a/lib/Form/Type/FieldType/DateTimeFieldType.php b/lib/Form/Type/FieldType/DateTimeFieldType.php
index 41a3ed15c..b807a9073 100644
--- a/lib/Form/Type/FieldType/DateTimeFieldType.php
+++ b/lib/Form/Type/FieldType/DateTimeFieldType.php
@@ -7,8 +7,10 @@
 
 use EzSystems\RepositoryForms\FieldType\DataTransformer\DateTimeValueTransformer;
 use Symfony\Component\Form\AbstractType;
-use Symfony\Component\Form\Extension\Core\Type\DateTimeType;
+use Symfony\Component\Form\Extension\Core\Type\IntegerType;
 use Symfony\Component\Form\FormBuilderInterface;
+use Symfony\Component\Form\FormInterface;
+use Symfony\Component\Form\FormView;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
@@ -28,34 +30,24 @@ public function getBlockPrefix()
 
     public function getParent()
     {
-        return DateTimeType::class;
+        return IntegerType::class;
     }
 
     public function buildForm(FormBuilderInterface $builder, array $options)
     {
         $builder
-            ->setAttributes($this->getAttributes($options))
             ->addModelTransformer(new DateTimeValueTransformer());
     }
 
-    private function getAttributes(array $options)
+    public function buildView(FormView $view, FormInterface $form, array $options)
     {
-        $attributes = [];
-
-        if ($options['with_seconds']) {
-            $attributes['step'] = 1;
-        }
-
-        return $attributes;
+        $view->vars['attr']['data-seconds'] = (int) $options['with_seconds'];
     }
 
     public function configureOptions(OptionsResolver $resolver)
     {
-        $resolver->setDefaults([
-            'input' => 'datetime',
-            'date_widget' => 'single_text',
-            'time_widget' => 'single_text',
-            'html5' => false,
-        ]);
+        $resolver
+            ->setDefault('with_seconds', true)
+            ->setAllowedTypes('with_seconds', 'bool');
     }
 }