diff --git a/src/EmailLexer.php b/src/EmailLexer.php
index a553f5b..5c3bf3a 100644
--- a/src/EmailLexer.php
+++ b/src/EmailLexer.php
@@ -252,8 +252,7 @@ class EmailLexer extends AbstractLexer
             return self::INVALID;
         }
 
-
-        return  self::GENERIC;
+        return self::GENERIC;
     }
 
     protected function isValid(string $value): bool
diff --git a/src/Parser/CommentStrategy/CommentStrategy.php b/src/Parser/CommentStrategy/CommentStrategy.php
index 410032f..8834db0 100644
--- a/src/Parser/CommentStrategy/CommentStrategy.php
+++ b/src/Parser/CommentStrategy/CommentStrategy.php
@@ -4,15 +4,19 @@ namespace Egulias\EmailValidator\Parser\CommentStrategy;
 
 use Egulias\EmailValidator\EmailLexer;
 use Egulias\EmailValidator\Result\Result;
+use Egulias\EmailValidator\Warning\Warning;
 
 interface CommentStrategy
 {
     /**
      * Return "true" to continue, "false" to exit
      */
-    public function exitCondition(EmailLexer $lexer, int $openedParenthesis) : bool;
+    public function exitCondition(EmailLexer $lexer, int $openedParenthesis): bool;
 
-    public function endOfLoopValidations(EmailLexer $lexer) : Result;
+    public function endOfLoopValidations(EmailLexer $lexer): Result;
 
-    public function getWarnings() : array;
+    /**
+     * @return Warning[]
+     */
+    public function getWarnings(): array;
 }
diff --git a/src/Parser/PartParser.php b/src/Parser/PartParser.php
index 7034e0b..d0ed5fd 100644
--- a/src/Parser/PartParser.php
+++ b/src/Parser/PartParser.php
@@ -7,11 +7,12 @@ use Egulias\EmailValidator\Result\InvalidEmail;
 use Egulias\EmailValidator\Result\Reason\ConsecutiveDot;
 use Egulias\EmailValidator\Result\Result;
 use Egulias\EmailValidator\Result\ValidEmail;
+use Egulias\EmailValidator\Warning\Warning;
 
 abstract class PartParser
 {
     /**
-     * @var array
+     * @var Warning[]
      */
     protected $warnings = [];
 
@@ -28,7 +29,7 @@ abstract class PartParser
     abstract public function parse(): Result;
 
     /**
-     * @return \Egulias\EmailValidator\Warning\Warning[]
+     * @return Warning[]
      */
     public function getWarnings()
     {
diff --git a/src/Result/InvalidEmail.php b/src/Result/InvalidEmail.php
index 4cc7a2e..82699ac 100644
--- a/src/Result/InvalidEmail.php
+++ b/src/Result/InvalidEmail.php
@@ -6,11 +6,15 @@ use Egulias\EmailValidator\Result\Reason\Reason;
 
 class InvalidEmail implements Result
 {
-    private $token;
+    /**
+     * @var string
+     */
+    private string $token;
+
     /**
      * @var Reason
      */
-    protected $reason;
+    protected Reason $reason;
 
     public function __construct(Reason $reason, string $token)
     {
diff --git a/src/Validation/DNSCheckValidation.php b/src/Validation/DNSCheckValidation.php
index 8350cc5..a17091f 100644
--- a/src/Validation/DNSCheckValidation.php
+++ b/src/Validation/DNSCheckValidation.php
@@ -9,6 +9,7 @@ use Egulias\EmailValidator\Result\Reason\LocalOrReservedDomain;
 use Egulias\EmailValidator\Result\Reason\NoDNSRecord as ReasonNoDNSRecord;
 use Egulias\EmailValidator\Result\Reason\UnableToGetDNSRecord;
 use Egulias\EmailValidator\Warning\NoDNSMXRecord;
+use Egulias\EmailValidator\Warning\Warning;
 
 class DNSCheckValidation implements EmailValidation
 {
@@ -20,6 +21,8 @@ class DNSCheckValidation implements EmailValidation
     /**
      * Reserved Top Level DNS Names (https://tools.ietf.org/html/rfc2606#section-2),
      * mDNS and private DNS Namespaces (https://tools.ietf.org/html/rfc6762#appendix-G)
+     * 
+     * @var string
      */
     public const RESERVED_DNS_TOP_LEVEL_NAMES = [
         // Reserved Top Level DNS Names
@@ -41,7 +44,7 @@ class DNSCheckValidation implements EmailValidation
     ];
 
     /**
-     * @var array
+     * @var Warning[]
      */
     private $warnings = [];
 
@@ -103,6 +106,9 @@ class DNSCheckValidation implements EmailValidation
         return $this->error;
     }
 
+    /**
+     * @return Warning[]
+     */
     public function getWarnings(): array
     {
         return $this->warnings;
diff --git a/src/Validation/DNSGetRecordWrapper.php b/src/Validation/DNSGetRecordWrapper.php
index f493c57..25e2fa0 100644
--- a/src/Validation/DNSGetRecordWrapper.php
+++ b/src/Validation/DNSGetRecordWrapper.php
@@ -1,4 +1,5 @@
 <?php
+
 namespace Egulias\EmailValidator\Validation;
 
 class DNSGetRecordWrapper
@@ -6,13 +7,15 @@ class DNSGetRecordWrapper
     /**
      * @param string $host
      * @param int $type
+     * 
+     * @return DNSRecords
      */
-    public function getRecords(string $host, int $type) : DNSRecords
+    public function getRecords(string $host, int $type): DNSRecords
     {
         // A workaround to fix https://bugs.php.net/bug.php?id=73149
         /** @psalm-suppress InvalidArgument */
         set_error_handler(
-            static function (int $errorLevel, string $errorMessage): ?bool {
+            static function (int $errorLevel, string $errorMessage): never {
                 throw new \RuntimeException("Unable to get DNS record for the host: $errorMessage");
             }
         );
diff --git a/src/Validation/DNSRecords.php b/src/Validation/DNSRecords.php
index b026a2d..3a9915d 100644
--- a/src/Validation/DNSRecords.php
+++ b/src/Validation/DNSRecords.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Validation;
 
 class DNSRecords
 {
-    
+
     /**
      * @var array $records
      */
@@ -15,21 +15,26 @@ class DNSRecords
      */
     private $error = false;
 
+    /**
+     * @param array $records
+     * @param bool $error
+     */
     public function __construct(array $records, bool $error = false)
     {
         $this->records = $records;
         $this->error = $error;
     }
 
-    public function getRecords() : array
+    /**
+     * @return array
+     */
+    public function getRecords(): array
     {
         return $this->records;
     }
 
-    public function withError() : bool
+    public function withError(): bool
     {
         return $this->error;
     }
-
-
 }
diff --git a/src/Validation/MessageIDValidation.php b/src/Validation/MessageIDValidation.php
index 0e02043..97d1ea7 100644
--- a/src/Validation/MessageIDValidation.php
+++ b/src/Validation/MessageIDValidation.php
@@ -6,12 +6,13 @@ use Egulias\EmailValidator\EmailLexer;
 use Egulias\EmailValidator\MessageIDParser;
 use Egulias\EmailValidator\Result\InvalidEmail;
 use Egulias\EmailValidator\Result\Reason\ExceptionFound;
+use Egulias\EmailValidator\Warning\Warning;
 
 class MessageIDValidation implements EmailValidation
 {
 
     /**
-     * @var array
+     * @var Warning[]
      */
     private $warnings = [];
 
@@ -39,6 +40,9 @@ class MessageIDValidation implements EmailValidation
         return true;
     }
 
+    /**
+     * @return Warning[]
+     */
     public function getWarnings(): array
     {
         return $this->warnings;
diff --git a/src/Validation/MultipleValidationWithAnd.php b/src/Validation/MultipleValidationWithAnd.php
index 7feb7c0..f23e84b 100644
--- a/src/Validation/MultipleValidationWithAnd.php
+++ b/src/Validation/MultipleValidationWithAnd.php
@@ -6,6 +6,7 @@ use Egulias\EmailValidator\EmailLexer;
 use Egulias\EmailValidator\Result\InvalidEmail;
 use Egulias\EmailValidator\Validation\Exception\EmptyValidationList;
 use Egulias\EmailValidator\Result\MultipleErrors;
+use Egulias\EmailValidator\Warning\Warning;
 
 class MultipleValidationWithAnd implements EmailValidation
 {
@@ -27,7 +28,7 @@ class MultipleValidationWithAnd implements EmailValidation
     private $validations = [];
 
     /**
-     * @var array
+     * @var Warning[]
      */
     private $warnings = [];
 
@@ -108,7 +109,7 @@ class MultipleValidationWithAnd implements EmailValidation
     }
 
     /**
-     * {@inheritdoc}
+     * @return Warning[]
      */
     public function getWarnings(): array
     {
diff --git a/src/Validation/RFCValidation.php b/src/Validation/RFCValidation.php
index e2c27ba..f5819d8 100644
--- a/src/Validation/RFCValidation.php
+++ b/src/Validation/RFCValidation.php
@@ -6,6 +6,7 @@ use Egulias\EmailValidator\EmailLexer;
 use Egulias\EmailValidator\EmailParser;
 use Egulias\EmailValidator\Result\InvalidEmail;
 use Egulias\EmailValidator\Result\Reason\ExceptionFound;
+use Egulias\EmailValidator\Warning\Warning;
 
 class RFCValidation implements EmailValidation
 {
@@ -15,16 +16,16 @@ class RFCValidation implements EmailValidation
     private $parser;
 
     /**
-     * @var array
+     * @var Warning[]
      */
-    private $warnings = [];
+    private array $warnings = [];
 
     /**
      * @var ?InvalidEmail
      */
     private $error;
 
-    public function isValid(string $email, EmailLexer $emailLexer) : bool
+    public function isValid(string $email, EmailLexer $emailLexer): bool
     {
         $this->parser = new EmailParser($emailLexer);
         try {
@@ -43,12 +44,15 @@ class RFCValidation implements EmailValidation
         return true;
     }
 
-    public function getError() : ?InvalidEmail
+    public function getError(): ?InvalidEmail
     {
         return $this->error;
     }
 
-    public function getWarnings() : array
+    /**
+     * @return Warning[]
+     */
+    public function getWarnings(): array
     {
         return $this->warnings;
     }
diff --git a/src/Warning/Warning.php b/src/Warning/Warning.php
index c3f62f6..e5b6ad8 100644
--- a/src/Warning/Warning.php
+++ b/src/Warning/Warning.php
@@ -4,6 +4,9 @@ namespace Egulias\EmailValidator\Warning;
 
 abstract class Warning
 {
+    /**
+     * @var int CODE
+     */
     public const CODE = 0;
 
     /**
@@ -45,6 +48,6 @@ abstract class Warning
      */
     public function __toString(): string
     {
-        return $this->message() . " rfc: " .  $this->rfcNumber . "internal code: " . static::CODE;
+        return $this->message() . " rfc: " .  $this->rfcNumber . "internal code: " . strval(static::CODE);
     }
 }