diff --git a/src/EmailValidator.php b/src/EmailValidator.php
index a30f21d..c68481e 100644
--- a/src/EmailValidator.php
+++ b/src/EmailValidator.php
@@ -2,7 +2,7 @@
 
 namespace Egulias\EmailValidator;
 
-use Egulias\EmailValidator\Exception\InvalidEmail;
+use Egulias\EmailValidator\Result\InvalidEmail;
 use Egulias\EmailValidator\Validation\EmailValidation;
 
 class EmailValidator
@@ -15,12 +15,12 @@ class EmailValidator
     /**
      * @var Warning\Warning[]
      */
-    protected $warnings = [];
+    private $warnings = [];
 
     /**
-     * @var InvalidEmail|null
+     * @var ?InvalidEmail
      */
-    protected $error;
+    private $error;
 
     public function __construct()
     {
diff --git a/src/Parser/Comment.php b/src/Parser/Comment.php
index bd77d57..3301242 100644
--- a/src/Parser/Comment.php
+++ b/src/Parser/Comment.php
@@ -13,8 +13,14 @@ use Egulias\EmailValidator\Warning\Comment as WarningComment;
 
 class Comment extends Parser
 {
-    //change to private when removed from parent parser
-    protected $openedParenthesis = 0;
+    /**
+     * @var int
+     */
+    private $openedParenthesis = 0;
+
+    /**
+     * @var CommentStrategy
+     */
     private $commentStrategy;
 
     public function __construct(EmailLexer $lexer, CommentStrategy $commentStrategy)
diff --git a/src/Parser/DomainLiteral.php b/src/Parser/DomainLiteral.php
index d338fcb..2055a4d 100644
--- a/src/Parser/DomainLiteral.php
+++ b/src/Parser/DomainLiteral.php
@@ -138,7 +138,7 @@ class DomainLiteral extends Parser
         }
     }
     
-    public function convertIPv4ToIPv6($addressLiteralIPv4) : string
+    public function convertIPv4ToIPv6(string $addressLiteralIPv4) : string
     {
         $matchesIP  = array();
         $IPv4Match = preg_match(
@@ -162,7 +162,7 @@ class DomainLiteral extends Parser
     /**
      * @param string $addressLiteral
      *
-     * @return string
+     * @return bool
      */
     protected function checkIPV4Tag($addressLiteral) : bool
     {
diff --git a/src/Parser/DomainPart.php b/src/Parser/DomainPart.php
index 96a6092..d1d2cb9 100644
--- a/src/Parser/DomainPart.php
+++ b/src/Parser/DomainPart.php
@@ -111,7 +111,7 @@ class DomainPart extends Parser
         return $this->domainPart;
     }
 
-    protected function parseComments()
+    protected function parseComments(): Result
     {
         $commentParser = new Comment($this->lexer, new DomainComment());
         $result = $commentParser->parse();
@@ -200,6 +200,9 @@ class DomainPart extends Parser
         return $result;
     }
 
+    /**
+     * @return InvalidEmail|ValidEmail
+     */
     protected function checkDomainPartExceptions(array $prev)
     {
         $invalidDomainTokens = array(
diff --git a/src/Parser/FoldingWhiteSpace.php b/src/Parser/FoldingWhiteSpace.php
index ba6bb48..0d131fb 100644
--- a/src/Parser/FoldingWhiteSpace.php
+++ b/src/Parser/FoldingWhiteSpace.php
@@ -46,6 +46,9 @@ class  FoldingWhiteSpace extends Parser
         return new ValidEmail();
     }
 
+    /**
+     * @return InvalidEmail|ValidEmail|null
+     */
     protected function checkCRLFInFWS()
     {
         if ($this->lexer->token['type'] !== EmailLexer::CRLF) {
diff --git a/src/Parser/LocalPart.php b/src/Parser/LocalPart.php
index 4906e55..8079dc6 100644
--- a/src/Parser/LocalPart.php
+++ b/src/Parser/LocalPart.php
@@ -114,7 +114,7 @@ class LocalPart extends Parser
         return $parseAgain;
     }
 
-    private function parseComments()
+    private function parseComments(): Result
     {
         $commentParser = new Comment($this->lexer, new LocalComment());
         $result = $commentParser->parse();
diff --git a/src/Validation/EmailValidation.php b/src/Validation/EmailValidation.php
index 36d53ae..66a4792 100644
--- a/src/Validation/EmailValidation.php
+++ b/src/Validation/EmailValidation.php
@@ -21,7 +21,7 @@ interface EmailValidation
     /**
      * Returns the validation error.
      *
-     * @return InvalidEmail|null
+     * @return InvalidEmail
      */
     public function getError() : ?InvalidEmail;