diff --git a/src/EmailLexer.php b/src/EmailLexer.php
index 7e660b6..0bfe86f 100644
--- a/src/EmailLexer.php
+++ b/src/EmailLexer.php
@@ -7,54 +7,54 @@ use Doctrine\Common\Lexer\AbstractLexer;
 class EmailLexer extends AbstractLexer
 {
     //ASCII values
-    const S_EMPTY            = null;
-    const C_NUL              = 0;
-    const S_HTAB             = 9;
-    const S_LF               = 10;
-    const S_CR               = 13;
-    const S_SP               = 32;
-    const EXCLAMATION        = 33;
-    const S_DQUOTE           = 34;
-    const NUMBER_SIGN        = 35;
-    const DOLLAR             = 36;
-    const PERCENTAGE         = 37;
-    const AMPERSAND          = 38;
-    const S_SQUOTE           = 39;
-    const S_OPENPARENTHESIS  = 40;
-    const S_CLOSEPARENTHESIS = 41;
-    const ASTERISK           = 42;
-    const S_PLUS             = 43;
-    const S_COMMA            = 44;
-    const S_HYPHEN           = 45;
-    const S_DOT              = 46;
-    const S_SLASH            = 47;
-    const S_COLON            = 58;
-    const S_SEMICOLON        = 59;
-    const S_LOWERTHAN        = 60;
-    const S_EQUAL            = 61;
-    const S_GREATERTHAN      = 62;
-    const QUESTIONMARK       = 63;
-    const S_AT               = 64;
-    const S_OPENBRACKET      = 91;
-    const S_BACKSLASH        = 92;
-    const S_CLOSEBRACKET     = 93;
-    const CARET              = 94;
-    const S_UNDERSCORE       = 95;
-    const S_BACKTICK         = 96;
-    const S_OPENCURLYBRACES  = 123;
-    const S_PIPE             = 124;
-    const S_CLOSECURLYBRACES = 125;
-    const S_TILDE            = 126;
-    const C_DEL              = 127;
-    const INVERT_QUESTIONMARK= 168;
-    const INVERT_EXCLAMATION = 173;
-    const GENERIC            = 300;
-    const S_IPV6TAG          = 301;
-    const INVALID            = 302;
-    const CRLF               = 1310;
-    const S_DOUBLECOLON      = 5858;
-    const ASCII_INVALID_FROM = 127;
-    const ASCII_INVALID_TO   = 199;
+    public const S_EMPTY            = null;
+    public const C_NUL              = 0;
+    public const S_HTAB             = 9;
+    public const S_LF               = 10;
+    public const S_CR               = 13;
+    public const S_SP               = 32;
+    public const EXCLAMATION        = 33;
+    public const S_DQUOTE           = 34;
+    public const NUMBER_SIGN        = 35;
+    public const DOLLAR             = 36;
+    public const PERCENTAGE         = 37;
+    public const AMPERSAND          = 38;
+    public const S_SQUOTE           = 39;
+    public const S_OPENPARENTHESIS  = 40;
+    public const S_CLOSEPARENTHESIS = 41;
+    public const ASTERISK           = 42;
+    public const S_PLUS             = 43;
+    public const S_COMMA            = 44;
+    public const S_HYPHEN           = 45;
+    public const S_DOT              = 46;
+    public const S_SLASH            = 47;
+    public const S_COLON            = 58;
+    public const S_SEMICOLON        = 59;
+    public const S_LOWERTHAN        = 60;
+    public const S_EQUAL            = 61;
+    public const S_GREATERTHAN      = 62;
+    public const QUESTIONMARK       = 63;
+    public const S_AT               = 64;
+    public const S_OPENBRACKET      = 91;
+    public const S_BACKSLASH        = 92;
+    public const S_CLOSEBRACKET     = 93;
+    public const CARET              = 94;
+    public const S_UNDERSCORE       = 95;
+    public const S_BACKTICK         = 96;
+    public const S_OPENCURLYBRACES  = 123;
+    public const S_PIPE             = 124;
+    public const S_CLOSECURLYBRACES = 125;
+    public const S_TILDE            = 126;
+    public const C_DEL              = 127;
+    public const INVERT_QUESTIONMARK= 168;
+    public const INVERT_EXCLAMATION = 173;
+    public const GENERIC            = 300;
+    public const S_IPV6TAG          = 301;
+    public const INVALID            = 302;
+    public const CRLF               = 1310;
+    public const S_DOUBLECOLON      = 5858;
+    public const ASCII_INVALID_FROM = 127;
+    public const ASCII_INVALID_TO   = 199;
 
     /**
      * US-ASCII visible characters not valid for atext (@link http://tools.ietf.org/html/rfc5322#section-3.2.3)
@@ -107,11 +107,11 @@ class EmailLexer extends AbstractLexer
         '¡'    => self::INVERT_EXCLAMATION,
     ];
 
-    const INVALID_CHARS_REGEX = "/[^\p{S}\p{C}\p{Cc}]+/iu";
+    public const INVALID_CHARS_REGEX = "/[^\p{S}\p{C}\p{Cc}]+/iu";
 
-    const VALID_UTF8_REGEX = '/\p{Cc}+/u';
+    public const VALID_UTF8_REGEX = '/\p{Cc}+/u';
 
-    const CATCHABLE_PATTERNS = [
+    public const CATCHABLE_PATTERNS = [
         '[a-zA-Z]+[46]?', //ASCII and domain literal
         '[^\x00-\x7F]',  //UTF-8
         '[0-9]+',
@@ -121,11 +121,11 @@ class EmailLexer extends AbstractLexer
         '.',
     ];
 
-    const NON_CATCHABLE_PATTERNS = [
+    public const NON_CATCHABLE_PATTERNS = [
         '[\xA0-\xff]+',
     ];
 
-    const MODIFIERS = 'iu';
+    public const MODIFIERS = 'iu';
 
     /** @var bool */
     protected $hasInvalidTokens = false;
diff --git a/src/EmailParser.php b/src/EmailParser.php
index cf22ab0..352eae4 100644
--- a/src/EmailParser.php
+++ b/src/EmailParser.php
@@ -12,7 +12,7 @@ use Egulias\EmailValidator\Result\Reason\NoLocalPart;
 
 class EmailParser extends Parser
 {
-    const EMAIL_MAX_LENGTH = 254;
+    public const EMAIL_MAX_LENGTH = 254;
 
     /**
      * @var string
diff --git a/src/MessageIDParser.php b/src/MessageIDParser.php
index 52e4a82..b0b6720 100644
--- a/src/MessageIDParser.php
+++ b/src/MessageIDParser.php
@@ -13,7 +13,7 @@ use Egulias\EmailValidator\Result\Reason\NoLocalPart;
 class MessageIDParser extends Parser
 {
 
-    const EMAILID_MAX_LENGTH = 254;
+    public const EMAILID_MAX_LENGTH = 254;
 
     /**
      * @var string
diff --git a/src/Parser/DomainLiteral.php b/src/Parser/DomainLiteral.php
index c668bf2..e6d66d0 100644
--- a/src/Parser/DomainLiteral.php
+++ b/src/Parser/DomainLiteral.php
@@ -22,9 +22,9 @@ use Egulias\EmailValidator\Warning\DomainLiteral as WarningDomainLiteral;
 
 class DomainLiteral extends PartParser
 {
-    const IPV4_REGEX = '/\\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/';
+    public const IPV4_REGEX = '/\\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/';
 
-    const OBSOLETE_WARNINGS = [
+    public const OBSOLETE_WARNINGS = [
         EmailLexer::INVALID,
         EmailLexer::C_DEL,
         EmailLexer::S_LF,
diff --git a/src/Parser/DomainPart.php b/src/Parser/DomainPart.php
index f171740..a57f4ba 100644
--- a/src/Parser/DomainPart.php
+++ b/src/Parser/DomainPart.php
@@ -24,8 +24,8 @@ use Egulias\EmailValidator\Parser\DomainLiteral as DomainLiteralParser;
 
 class DomainPart extends PartParser
 {
-    const DOMAIN_MAX_LENGTH = 253;
-    const LABEL_MAX_LENGTH = 63;
+    public const DOMAIN_MAX_LENGTH = 253;
+    public const LABEL_MAX_LENGTH = 63;
 
     /**
      * @var string
diff --git a/src/Parser/FoldingWhiteSpace.php b/src/Parser/FoldingWhiteSpace.php
index a332963..fff6ec3 100644
--- a/src/Parser/FoldingWhiteSpace.php
+++ b/src/Parser/FoldingWhiteSpace.php
@@ -15,7 +15,7 @@ use Egulias\EmailValidator\Result\ValidEmail;
 
 class  FoldingWhiteSpace extends PartParser
 {
-    const FWS_TYPES = [
+    public const FWS_TYPES = [
         EmailLexer::S_SP,
         EmailLexer::S_HTAB,
         EmailLexer::S_CR,
diff --git a/src/Parser/LocalPart.php b/src/Parser/LocalPart.php
index 5ed395c..154521b 100644
--- a/src/Parser/LocalPart.php
+++ b/src/Parser/LocalPart.php
@@ -15,7 +15,7 @@ use Egulias\EmailValidator\Parser\CommentStrategy\LocalComment;
 
 class LocalPart extends PartParser
 {
-    const INVALID_TOKENS = [
+    public const INVALID_TOKENS = [
         EmailLexer::S_COMMA => EmailLexer::S_COMMA,
         EmailLexer::S_CLOSEBRACKET => EmailLexer::S_CLOSEBRACKET,
         EmailLexer::S_OPENBRACKET => EmailLexer::S_OPENBRACKET,
diff --git a/src/Result/InvalidEmail.php b/src/Result/InvalidEmail.php
index 858bae4..180f4d8 100644
--- a/src/Result/InvalidEmail.php
+++ b/src/Result/InvalidEmail.php
@@ -6,7 +6,7 @@ use Egulias\EmailValidator\Result\Reason\Reason;
 
 class InvalidEmail implements Result
 {
-    private  $token;
+    private $token;
     /**
      * @var Reason
      */
diff --git a/src/Result/Reason/CRLFAtTheEnd.php b/src/Result/Reason/CRLFAtTheEnd.php
index a0b66e7..185b9eb 100644
--- a/src/Result/Reason/CRLFAtTheEnd.php
+++ b/src/Result/Reason/CRLFAtTheEnd.php
@@ -4,8 +4,8 @@ namespace Egulias\EmailValidator\Result\Reason;
 
 class CRLFAtTheEnd implements Reason
 {
-    const CODE = 149;
-    const REASON = "CRLF at the end";
+    public const CODE = 149;
+    public const REASON = "CRLF at the end";
 
     public function code() : int
     {
diff --git a/src/Validation/DNSCheckValidation.php b/src/Validation/DNSCheckValidation.php
index b8fd41c..9989aa4 100644
--- a/src/Validation/DNSCheckValidation.php
+++ b/src/Validation/DNSCheckValidation.php
@@ -21,7 +21,7 @@ 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)
      */
-    const RESERVED_DNS_TOP_LEVEL_NAMES = [
+    public const RESERVED_DNS_TOP_LEVEL_NAMES = [
         // Reserved Top Level DNS Names
         'test',
         'example',
diff --git a/src/Validation/MultipleValidationWithAnd.php b/src/Validation/MultipleValidationWithAnd.php
index 90d4f0d..abafe75 100644
--- a/src/Validation/MultipleValidationWithAnd.php
+++ b/src/Validation/MultipleValidationWithAnd.php
@@ -13,13 +13,13 @@ class MultipleValidationWithAnd implements EmailValidation
      * If one of validations fails, the remaining validations will be skipped.
      * This means MultipleErrors will only contain a single error, the first found.
      */
-    const STOP_ON_ERROR = 0;
+    public const STOP_ON_ERROR = 0;
 
     /**
      * All of validations will be invoked even if one of them got failure.
      * So MultipleErrors will contain all causes.
      */
-    const ALLOW_ALL_ERRORS = 1;
+    public const ALLOW_ALL_ERRORS = 1;
 
     /**
      * @var EmailValidation[]
diff --git a/src/Warning/AddressLiteral.php b/src/Warning/AddressLiteral.php
index 77e70f7..474ff0e 100644
--- a/src/Warning/AddressLiteral.php
+++ b/src/Warning/AddressLiteral.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class AddressLiteral extends Warning
 {
-    const CODE = 12;
+    public const CODE = 12;
 
     public function __construct()
     {
diff --git a/src/Warning/CFWSNearAt.php b/src/Warning/CFWSNearAt.php
index be43bbe..8bac12b 100644
--- a/src/Warning/CFWSNearAt.php
+++ b/src/Warning/CFWSNearAt.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class CFWSNearAt extends Warning
 {
-    const CODE = 49;
+    public const CODE = 49;
 
     public function __construct()
     {
diff --git a/src/Warning/CFWSWithFWS.php b/src/Warning/CFWSWithFWS.php
index dea3450..ba57601 100644
--- a/src/Warning/CFWSWithFWS.php
+++ b/src/Warning/CFWSWithFWS.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class CFWSWithFWS extends Warning
 {
-    const CODE = 18;
+    public const CODE = 18;
 
     public function __construct()
     {
diff --git a/src/Warning/Comment.php b/src/Warning/Comment.php
index 704c290..6508295 100644
--- a/src/Warning/Comment.php
+++ b/src/Warning/Comment.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class Comment extends Warning
 {
-    const CODE = 17;
+    public const CODE = 17;
 
     public function __construct()
     {
diff --git a/src/Warning/DeprecatedComment.php b/src/Warning/DeprecatedComment.php
index ad43bd7..a257807 100644
--- a/src/Warning/DeprecatedComment.php
+++ b/src/Warning/DeprecatedComment.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class DeprecatedComment extends Warning
 {
-    const CODE = 37;
+    public const CODE = 37;
 
     public function __construct()
     {
diff --git a/src/Warning/DomainLiteral.php b/src/Warning/DomainLiteral.php
index 6f36b5e..034388c 100644
--- a/src/Warning/DomainLiteral.php
+++ b/src/Warning/DomainLiteral.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class DomainLiteral extends Warning
 {
-    const CODE = 70;
+    public const CODE = 70;
 
     public function __construct()
     {
diff --git a/src/Warning/EmailTooLong.php b/src/Warning/EmailTooLong.php
index 497309d..d25ad12 100644
--- a/src/Warning/EmailTooLong.php
+++ b/src/Warning/EmailTooLong.php
@@ -6,7 +6,7 @@ use Egulias\EmailValidator\EmailParser;
 
 class EmailTooLong extends Warning
 {
-    const CODE = 66;
+    public const CODE = 66;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6BadChar.php b/src/Warning/IPV6BadChar.php
index ba2fcc0..3ecd5bc 100644
--- a/src/Warning/IPV6BadChar.php
+++ b/src/Warning/IPV6BadChar.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6BadChar extends Warning
 {
-    const CODE = 74;
+    public const CODE = 74;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6ColonEnd.php b/src/Warning/IPV6ColonEnd.php
index 41afa78..3f0c2f2 100644
--- a/src/Warning/IPV6ColonEnd.php
+++ b/src/Warning/IPV6ColonEnd.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6ColonEnd extends Warning
 {
-    const CODE = 77;
+    public const CODE = 77;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6ColonStart.php b/src/Warning/IPV6ColonStart.php
index 1bf754e..742fb3b 100644
--- a/src/Warning/IPV6ColonStart.php
+++ b/src/Warning/IPV6ColonStart.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6ColonStart extends Warning
 {
-    const CODE = 76;
+    public const CODE = 76;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6Deprecated.php b/src/Warning/IPV6Deprecated.php
index d752caa..59c3037 100644
--- a/src/Warning/IPV6Deprecated.php
+++ b/src/Warning/IPV6Deprecated.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6Deprecated extends Warning
 {
-    const CODE = 13;
+    public const CODE = 13;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6DoubleColon.php b/src/Warning/IPV6DoubleColon.php
index 4f82394..d406602 100644
--- a/src/Warning/IPV6DoubleColon.php
+++ b/src/Warning/IPV6DoubleColon.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6DoubleColon extends Warning
 {
-    const CODE = 73;
+    public const CODE = 73;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6GroupCount.php b/src/Warning/IPV6GroupCount.php
index a59d317..551bc3a 100644
--- a/src/Warning/IPV6GroupCount.php
+++ b/src/Warning/IPV6GroupCount.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6GroupCount extends Warning
 {
-    const CODE = 72;
+    public const CODE = 72;
 
     public function __construct()
     {
diff --git a/src/Warning/IPV6MaxGroups.php b/src/Warning/IPV6MaxGroups.php
index 936274c..7f8a410 100644
--- a/src/Warning/IPV6MaxGroups.php
+++ b/src/Warning/IPV6MaxGroups.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class IPV6MaxGroups extends Warning
 {
-    const CODE = 75;
+    public const CODE = 75;
 
     public function __construct()
     {
diff --git a/src/Warning/LocalTooLong.php b/src/Warning/LocalTooLong.php
index 0d08d8b..b46b874 100644
--- a/src/Warning/LocalTooLong.php
+++ b/src/Warning/LocalTooLong.php
@@ -4,8 +4,8 @@ namespace Egulias\EmailValidator\Warning;
 
 class LocalTooLong extends Warning
 {
-    const CODE = 64;
-    const LOCAL_PART_LENGTH = 64;
+    public const CODE = 64;
+    public const LOCAL_PART_LENGTH = 64;
 
     public function __construct()
     {
diff --git a/src/Warning/NoDNSMXRecord.php b/src/Warning/NoDNSMXRecord.php
index b3c21a1..bddb96b 100644
--- a/src/Warning/NoDNSMXRecord.php
+++ b/src/Warning/NoDNSMXRecord.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class NoDNSMXRecord extends Warning
 {
-    const CODE = 6;
+    public const CODE = 6;
 
     public function __construct()
     {
diff --git a/src/Warning/ObsoleteDTEXT.php b/src/Warning/ObsoleteDTEXT.php
index 10f19e3..412fd49 100644
--- a/src/Warning/ObsoleteDTEXT.php
+++ b/src/Warning/ObsoleteDTEXT.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class ObsoleteDTEXT extends Warning
 {
-    const CODE = 71;
+    public const CODE = 71;
 
     public function __construct()
     {
diff --git a/src/Warning/QuotedPart.php b/src/Warning/QuotedPart.php
index 36a4265..afa1f9e 100644
--- a/src/Warning/QuotedPart.php
+++ b/src/Warning/QuotedPart.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class QuotedPart extends Warning
 {
-    const CODE = 36;
+    public const CODE = 36;
 
     /**
      * @param scalar $prevToken
diff --git a/src/Warning/QuotedString.php b/src/Warning/QuotedString.php
index 817e4e8..c152ec2 100644
--- a/src/Warning/QuotedString.php
+++ b/src/Warning/QuotedString.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class QuotedString extends Warning
 {
-    const CODE = 11;
+    public const CODE = 11;
 
     /**
      * @param scalar $prevToken
diff --git a/src/Warning/TLD.php b/src/Warning/TLD.php
index 2338b9f..10cec28 100644
--- a/src/Warning/TLD.php
+++ b/src/Warning/TLD.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 class TLD extends Warning
 {
-    const CODE = 9;
+    public const CODE = 9;
 
     public function __construct()
     {
diff --git a/src/Warning/Warning.php b/src/Warning/Warning.php
index a0158a2..8b39d64 100644
--- a/src/Warning/Warning.php
+++ b/src/Warning/Warning.php
@@ -4,7 +4,7 @@ namespace Egulias\EmailValidator\Warning;
 
 abstract class Warning
 {
-    const CODE = 0;
+    public const CODE = 0;
 
     /**
      * @var string