diff --git a/src/Resources/config/services/validator.xml b/src/Resources/config/services/validator.xml
index e58c614..e972608 100644
--- a/src/Resources/config/services/validator.xml
+++ b/src/Resources/config/services/validator.xml
@@ -4,12 +4,8 @@
            xmlns="http://symfony.com/schema/dic/services"
            xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
     <services>
-        <defaults public="true"/>
-
-        <service id="setono_sylius_catalog_promotion.validator.date_range"
-                 class="Setono\SyliusCatalogPromotionPlugin\Validator\Constraints\PromotionDateRangeValidator">
-            <tag name="validator.constraint_validator"
-                 alias="setono_sylius_catalog_promotion_promotion_date_range_validator"/>
+        <service id="Setono\SyliusCatalogPromotionPlugin\Validator\Constraints\PromotionDateRangeValidator">
+            <tag name="validator.constraint_validator"/>
         </service>
     </services>
 </container>
diff --git a/src/Resources/config/validation/Promotion.xml b/src/Resources/config/validation/Promotion.xml
index 96cb164..8dccb8f 100644
--- a/src/Resources/config/validation/Promotion.xml
+++ b/src/Resources/config/validation/Promotion.xml
@@ -11,7 +11,6 @@
             <option name="groups">setono_sylius_catalog_promotion</option>
         </constraint>
         <constraint name="Setono\SyliusCatalogPromotionPlugin\Validator\Constraints\PromotionDateRange">
-            <option name="message">setono_sylius_catalog_promotion.promotion.end_date_cannot_be_set_prior_start_date</option>
             <option name="groups">setono_sylius_catalog_promotion</option>
         </constraint>
         <property name="code">
diff --git a/src/Resources/translations/validators.en.yaml b/src/Resources/translations/validators.en.yaml
index 5853a16..0e7cd58 100644
--- a/src/Resources/translations/validators.en.yaml
+++ b/src/Resources/translations/validators.en.yaml
@@ -5,4 +5,4 @@ setono_sylius_catalog_promotion:
             regex: Promotion code can only be comprised of letters (a-z), numbers (0-9), dashes (-) and underscores (_).
         discount:
             range: Please enter value between 0% and 100%.
-        end_date_cannot_be_set_prior_start_date: End date cannot be set prior start date.
+        end_date_cannot_be_set_prior_start_date: End date must be set after start date.
diff --git a/src/Validator/Constraints/PromotionDateRange.php b/src/Validator/Constraints/PromotionDateRange.php
index 7503844..4016bad 100644
--- a/src/Validator/Constraints/PromotionDateRange.php
+++ b/src/Validator/Constraints/PromotionDateRange.php
@@ -14,9 +14,4 @@ public function getTargets(): string
     {
         return self::CLASS_CONSTRAINT;
     }
-
-    public function validatedBy(): string
-    {
-        return 'setono_sylius_catalog_promotion_promotion_date_range_validator';
-    }
 }
diff --git a/src/Validator/Constraints/PromotionDateRangeValidator.php b/src/Validator/Constraints/PromotionDateRangeValidator.php
index f9b2a55..61ed8f1 100644
--- a/src/Validator/Constraints/PromotionDateRangeValidator.php
+++ b/src/Validator/Constraints/PromotionDateRangeValidator.php
@@ -7,7 +7,8 @@
 use Setono\SyliusCatalogPromotionPlugin\Model\PromotionInterface;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
-use Webmozart\Assert\Assert;
+use Symfony\Component\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Validator\Exception\UnexpectedValueException;
 
 final class PromotionDateRangeValidator extends ConstraintValidator
 {
@@ -21,8 +22,13 @@ public function validate($value, Constraint $constraint): void
             return;
         }
 
-        Assert::isInstanceOf($value, PromotionInterface::class);
-        Assert::isInstanceOf($constraint, PromotionDateRange::class);
+        if (!$constraint instanceof PromotionDateRange) {
+            throw new UnexpectedTypeException($constraint, PromotionDateRange::class);
+        }
+
+        if (!$value instanceof PromotionInterface) {
+            throw new UnexpectedValueException($value, PromotionInterface::class);
+        }
 
         $startsAt = $value->getStartsAt();
         $endsAt = $value->getEndsAt();
@@ -31,7 +37,7 @@ public function validate($value, Constraint $constraint): void
             return;
         }
 
-        if ($startsAt->getTimestamp() > $endsAt->getTimestamp()) {
+        if ($startsAt > $endsAt) {
             $this->context
                 ->buildViolation($constraint->message)
                 ->atPath('endsAt')