diff --git a/library/Rules/AbstractSearcher.php b/library/Rules/AbstractSearcher.php
index f73d9630..b749bb38 100644
--- a/library/Rules/AbstractSearcher.php
+++ b/library/Rules/AbstractSearcher.php
@@ -13,7 +13,6 @@ use Respect\Validation\Helpers\CanValidateUndefined;
 
 use function in_array;
 use function is_scalar;
-use function mb_strtoupper;
 
 /**
  * Abstract class for searches into arrays.
@@ -45,6 +44,6 @@ abstract class AbstractSearcher extends AbstractRule
             return false;
         }
 
-        return in_array(mb_strtoupper((string) $input), $dataSource, true);
+        return in_array((string) $input, $dataSource, true);
     }
 }
diff --git a/library/Rules/PublicDomainSuffix.php b/library/Rules/PublicDomainSuffix.php
index 67f07ac6..d25980b4 100644
--- a/library/Rules/PublicDomainSuffix.php
+++ b/library/Rules/PublicDomainSuffix.php
@@ -9,29 +9,34 @@ declare(strict_types=1);
 
 namespace Respect\Validation\Rules;
 
+use Respect\Validation\Helpers\CanValidateUndefined;
 use Respect\Validation\Helpers\DomainInfo;
 
 use function array_pop;
 use function explode;
+use function in_array;
+use function is_scalar;
+use function strtoupper;
 
-final class PublicDomainSuffix extends AbstractSearcher
+final class PublicDomainSuffix extends AbstractRule
 {
-    /**
-     * @var string[]
-     */
-    private $domainInfo;
+    use CanValidateUndefined;
 
-    /**
-     * {@inheritDoc}
-     */
-    protected function getDataSource($input = null): array
+    public function validate($input): bool
     {
-        $parts = explode('.', $input);
+        if (!is_scalar($input)) {
+            return false;
+        }
+
+        $parts = explode('.', (string) $input);
         $tld = array_pop($parts);
 
         $domainInfo = new DomainInfo($tld);
-        $this->domainInfo = $domainInfo->getPublicSuffixes();
+        $dataSource = $domainInfo->getPublicSuffixes();
+        if ($this->isUndefined($input) && empty($dataSource)) {
+            return true;
+        }
 
-        return $this->domainInfo;
+        return in_array(strtoupper((string) $input), $dataSource, true);
     }
 }
diff --git a/tests/unit/Rules/CountryCodeTest.php b/tests/unit/Rules/CountryCodeTest.php
index 408ef324..17c7a497 100644
--- a/tests/unit/Rules/CountryCodeTest.php
+++ b/tests/unit/Rules/CountryCodeTest.php
@@ -61,6 +61,7 @@ final class CountryCodeTest extends RuleTestCase
     public static function providerForInvalidInput(): array
     {
         return [
+            [new CountryCode(),  'ca'],
             [new CountryCode(CountryCode::ALPHA2),  'USA'],
             [new CountryCode(CountryCode::ALPHA3),  'US'],
             [new CountryCode(CountryCode::NUMERIC), '000'],
diff --git a/tests/unit/Rules/PublicDomainSuffixTest.php b/tests/unit/Rules/PublicDomainSuffixTest.php
index 487e5967..53faa53b 100644
--- a/tests/unit/Rules/PublicDomainSuffixTest.php
+++ b/tests/unit/Rules/PublicDomainSuffixTest.php
@@ -10,6 +10,7 @@ declare(strict_types=1);
 namespace Respect\Validation\Rules;
 
 use Respect\Validation\Test\RuleTestCase;
+use stdClass;
 
 /**
  * @covers \Respect\Validation\Exceptions\PublicDomainSuffixException
@@ -41,6 +42,9 @@ final class PublicDomainSuffixTest extends RuleTestCase
         $rule = new PublicDomainSuffix();
 
         return [
+            [$rule, []],
+            [$rule, null],
+            [$rule, new stdClass()],
             [$rule, 'NONONONONONONONONON'],
             [$rule, 'NONONONONONONONONON.uk'],
             [$rule, 'invalid.com'],