diff --git a/examples/svgModuleJitter.php b/examples/svgModuleJitter.php
index e3aa38a90..cdb4020f2 100644
--- a/examples/svgModuleJitter.php
+++ b/examples/svgModuleJitter.php
@@ -26,7 +26,7 @@ require_once __DIR__.'/../vendor/autoload.php';
  */
 class ModuleJitterSVGoutput extends QRMarkupSVG{
 
-	protected const ROUND_PRECISION = 5;
+	protected const int ROUND_PRECISION = 5;
 
 	protected readonly float $sideLength;
 
diff --git a/src/Common/ECICharset.php b/src/Common/ECICharset.php
index d6f78b743..72ab66426 100644
--- a/src/Common/ECICharset.php
+++ b/src/Common/ECICharset.php
@@ -20,44 +20,44 @@ use function sprintf;
  */
 final class ECICharset{
 
-	public const CP437                 = 0;  // Code page 437, DOS Latin US
-	public const ISO_IEC_8859_1_GLI    = 1;  // GLI encoding with characters 0 to 127 identical to ISO/IEC 646 and characters 128 to 255 identical to ISO 8859-1
-	public const CP437_WO_GLI          = 2;  // An equivalent code table to CP437, without the return-to-GLI 0 logic
-	public const ISO_IEC_8859_1        = 3;  // Latin-1 (Default)
-	public const ISO_IEC_8859_2        = 4;  // Latin-2
-	public const ISO_IEC_8859_3        = 5;  // Latin-3
-	public const ISO_IEC_8859_4        = 6;  // Latin-4
-	public const ISO_IEC_8859_5        = 7;  // Latin/Cyrillic
-	public const ISO_IEC_8859_6        = 8;  // Latin/Arabic
-	public const ISO_IEC_8859_7        = 9;  // Latin/Greek
-	public const ISO_IEC_8859_8        = 10; // Latin/Hebrew
-	public const ISO_IEC_8859_9        = 11; // Latin-5
-	public const ISO_IEC_8859_10       = 12; // Latin-6
-	public const ISO_IEC_8859_11       = 13; // Latin/Thai
+	public const int CP437                 = 0;  // Code page 437, DOS Latin US
+	public const int ISO_IEC_8859_1_GLI    = 1;  // GLI encoding with characters 0 to 127 identical to ISO/IEC 646 and characters 128 to 255 identical to ISO 8859-1
+	public const int CP437_WO_GLI          = 2;  // An equivalent code table to CP437, without the return-to-GLI 0 logic
+	public const int ISO_IEC_8859_1        = 3;  // Latin-1 (Default)
+	public const int ISO_IEC_8859_2        = 4;  // Latin-2
+	public const int ISO_IEC_8859_3        = 5;  // Latin-3
+	public const int ISO_IEC_8859_4        = 6;  // Latin-4
+	public const int ISO_IEC_8859_5        = 7;  // Latin/Cyrillic
+	public const int ISO_IEC_8859_6        = 8;  // Latin/Arabic
+	public const int ISO_IEC_8859_7        = 9;  // Latin/Greek
+	public const int ISO_IEC_8859_8        = 10; // Latin/Hebrew
+	public const int ISO_IEC_8859_9        = 11; // Latin-5
+	public const int ISO_IEC_8859_10       = 12; // Latin-6
+	public const int ISO_IEC_8859_11       = 13; // Latin/Thai
 	// 14 reserved
-	public const ISO_IEC_8859_13       = 15; // Latin-7 (Baltic Rim)
-	public const ISO_IEC_8859_14       = 16; // Latin-8 (Celtic)
-	public const ISO_IEC_8859_15       = 17; // Latin-9
-	public const ISO_IEC_8859_16       = 18; // Latin-10
+	public const int ISO_IEC_8859_13       = 15; // Latin-7 (Baltic Rim)
+	public const int ISO_IEC_8859_14       = 16; // Latin-8 (Celtic)
+	public const int ISO_IEC_8859_15       = 17; // Latin-9
+	public const int ISO_IEC_8859_16       = 18; // Latin-10
 	// 19 reserved
-	public const SHIFT_JIS             = 20; // JIS X 0208 Annex 1 + JIS X 0201
-	public const WINDOWS_1250_LATIN_2  = 21; // Superset of Latin-2, Central Europe
-	public const WINDOWS_1251_CYRILLIC = 22; // Latin/Cyrillic
-	public const WINDOWS_1252_LATIN_1  = 23; // Superset of Latin-1
-	public const WINDOWS_1256_ARABIC   = 24;
-	public const ISO_IEC_10646_UCS_2   = 25; // High order byte first (UTF-16BE)
-	public const ISO_IEC_10646_UTF_8   = 26; // UTF-8
-	public const ISO_IEC_646_1991      = 27; // International Reference Version of ISO 7-bit coded character set (US-ASCII)
-	public const BIG5                  = 28; // Big 5 (Taiwan) Chinese Character Set
-	public const GB18030               = 29; // GB (PRC) Chinese Character Set
-	public const EUC_KR                = 30; // Korean Character Set
+	public const int SHIFT_JIS             = 20; // JIS X 0208 Annex 1 + JIS X 0201
+	public const int WINDOWS_1250_LATIN_2  = 21; // Superset of Latin-2, Central Europe
+	public const int WINDOWS_1251_CYRILLIC = 22; // Latin/Cyrillic
+	public const int WINDOWS_1252_LATIN_1  = 23; // Superset of Latin-1
+	public const int WINDOWS_1256_ARABIC   = 24;
+	public const int ISO_IEC_10646_UCS_2   = 25; // High order byte first (UTF-16BE)
+	public const int ISO_IEC_10646_UTF_8   = 26; // UTF-8
+	public const int ISO_IEC_646_1991      = 27; // International Reference Version of ISO 7-bit coded character set (US-ASCII)
+	public const int BIG5                  = 28; // Big 5 (Taiwan) Chinese Character Set
+	public const int GB18030               = 29; // GB (PRC) Chinese Character Set
+	public const int EUC_KR                = 30; // Korean Character Set
 
 	/**
 	 * map of charset id -> name
 	 *
 	 * @see \mb_list_encodings()
 	 */
-	public const MB_ENCODINGS = [
+	public const array MB_ENCODINGS = [
 		self::CP437                 => null,
 		self::ISO_IEC_8859_1_GLI    => null,
 		self::CP437_WO_GLI          => null,
diff --git a/src/Common/EccLevel.php b/src/Common/EccLevel.php
index ae7720433..1e525e0eb 100644
--- a/src/Common/EccLevel.php
+++ b/src/Common/EccLevel.php
@@ -21,21 +21,17 @@ final class EccLevel{
 
 	// ISO/IEC 18004:2000 Tables 12, 25
 
-	/** @var int */
-	public const L = 0b01; // 7%.
-	/** @var int */
-	public const M = 0b00; // 15%.
-	/** @var int */
-	public const Q = 0b11; // 25%.
-	/** @var int */
-	public const H = 0b10; // 30%.
+	public const int L = 0b01; // 7%.
+	public const int M = 0b00; // 15%.
+	public const int Q = 0b11; // 25%.
+	public const int H = 0b10; // 30%.
 
 	/**
 	 * ISO/IEC 18004:2000 Tables 7-11 - Number of symbol characters and input data capacity for versions 1 to 40
 	 *
 	 * @var int[][]
 	 */
-	private const MAX_BITS = [
+	private const array MAX_BITS = [
 	//	[    L,     M,     Q,     H]  // v  => modules
 		[    0,     0,     0,     0], // 0  =>  will be ignored, index starts at 1
 		[  152,   128,   104,    72], // 1  =>  21
@@ -87,7 +83,7 @@ final class EccLevel{
 	 *
 	 * @var int[][]
 	 */
-	private const FORMAT_PATTERN = [
+	private const array FORMAT_PATTERN = [
 		[ // L
 		  0b111011111000100,
 		  0b111001011110011,
diff --git a/src/Common/GF256.php b/src/Common/GF256.php
index f3e4fd5ee..f8deec0e7 100644
--- a/src/Common/GF256.php
+++ b/src/Common/GF256.php
@@ -35,7 +35,7 @@ final class GF256{
 	 */
 #	private int $primitive = 0x011D;
 
-	private const logTable = [
+	private const array logTable = [
 		  0, // the first value is never returned, index starts at 1
 		       0,   1,  25,   2,  50,  26, 198,   3, 223,  51, 238,  27, 104, 199,  75,
 		  4, 100, 224,  14,  52, 141, 239, 129,  28, 193, 105, 248, 200,   8,  76, 113,
@@ -55,7 +55,7 @@ final class GF256{
 		 79, 174, 213, 233, 230, 231, 173, 232, 116, 214, 244, 234, 168,  80,  88, 175,
 	];
 
-	private const expTable = [
+	private const array expTable = [
 		  1,   2,   4,   8,  16,  32,  64, 128,  29,  58, 116, 232, 205, 135,  19,  38,
 		 76, 152,  45,  90, 180, 117, 234, 201, 143,   3,   6,  12,  24,  48,  96, 192,
 		157,  39,  78, 156,  37,  74, 148,  53, 106, 212, 181, 119, 238, 193, 159,  35,
diff --git a/src/Common/MaskPattern.php b/src/Common/MaskPattern.php
index 106fc5922..832a6bf4b 100644
--- a/src/Common/MaskPattern.php
+++ b/src/Common/MaskPattern.php
@@ -28,24 +28,22 @@ final class MaskPattern{
 
 	/**
 	 * @see \chillerlan\QRCode\QROptionsTrait::$maskPattern
-	 *
-	 * @var int
 	 */
-	public const AUTO = -1;
+	public const int AUTO = -1;
 
-	public const PATTERN_000 = 0b000;
-	public const PATTERN_001 = 0b001;
-	public const PATTERN_010 = 0b010;
-	public const PATTERN_011 = 0b011;
-	public const PATTERN_100 = 0b100;
-	public const PATTERN_101 = 0b101;
-	public const PATTERN_110 = 0b110;
-	public const PATTERN_111 = 0b111;
+	public const int PATTERN_000 = 0b000;
+	public const int PATTERN_001 = 0b001;
+	public const int PATTERN_010 = 0b010;
+	public const int PATTERN_011 = 0b011;
+	public const int PATTERN_100 = 0b100;
+	public const int PATTERN_101 = 0b101;
+	public const int PATTERN_110 = 0b110;
+	public const int PATTERN_111 = 0b111;
 
 	/**
 	 * @var int[]
 	 */
-	public const PATTERNS = [
+	public const array PATTERNS = [
 		self::PATTERN_000,
 		self::PATTERN_001,
 		self::PATTERN_010,
@@ -61,10 +59,10 @@ final class MaskPattern{
 	 *
 	 * ISO/IEC 18004:2000 Section 8.8.1 - Table 24
 	 */
-	private const PENALTY_N1 = 3;
-	private const PENALTY_N2 = 3;
-	private const PENALTY_N3 = 40;
-	private const PENALTY_N4 = 10;
+	private const int PENALTY_N1 = 3;
+	private const int PENALTY_N2 = 3;
+	private const int PENALTY_N3 = 40;
+	private const int PENALTY_N4 = 10;
 
 	/**
 	 * The current mask pattern value (0-7)
diff --git a/src/Common/Mode.php b/src/Common/Mode.php
index e3847f98f..f1a9780fa 100644
--- a/src/Common/Mode.php
+++ b/src/Common/Mode.php
@@ -21,33 +21,23 @@ final class Mode{
 
 	// ISO/IEC 18004:2000 Table 2
 
-	/** @var int */
-	public const TERMINATOR       = 0b0000;
-	/** @var int */
-	public const NUMBER           = 0b0001;
-	/** @var int */
-	public const ALPHANUM         = 0b0010;
-	/** @var int */
-	public const BYTE             = 0b0100;
-	/** @var int */
-	public const KANJI            = 0b1000;
-	/** @var int */
-	public const HANZI            = 0b1101;
-	/** @var int */
-	public const STRCTURED_APPEND = 0b0011;
-	/** @var int */
-	public const FNC1_FIRST       = 0b0101;
-	/** @var int */
-	public const FNC1_SECOND      = 0b1001;
-	/** @var int */
-	public const ECI              = 0b0111;
+	public const int TERMINATOR       = 0b0000;
+	public const int NUMBER           = 0b0001;
+	public const int ALPHANUM         = 0b0010;
+	public const int BYTE             = 0b0100;
+	public const int KANJI            = 0b1000;
+	public const int HANZI            = 0b1101;
+	public const int STRCTURED_APPEND = 0b0011;
+	public const int FNC1_FIRST       = 0b0101;
+	public const int FNC1_SECOND      = 0b1001;
+	public const int ECI              = 0b0111;
 
 	/**
 	 * mode length bits for the version breakpoints 1-9, 10-26 and 27-40
 	 *
 	 * ISO/IEC 18004:2000 Table 3 - Number of bits in Character Count Indicator
 	 */
-	public const LENGTH_BITS = [
+	public const array LENGTH_BITS = [
 		self::NUMBER   => [10, 12, 14],
 		self::ALPHANUM => [ 9, 11, 13],
 		self::BYTE     => [ 8, 16, 16],
@@ -61,7 +51,7 @@ final class Mode{
 	 *
 	 * @var array<int, string>
 	 */
-	public const INTERFACES = [
+	public const array INTERFACES = [
 		self::NUMBER   => Number::class,
 		self::ALPHANUM => AlphaNum::class,
 		self::KANJI    => Kanji::class,
diff --git a/src/Common/Version.php b/src/Common/Version.php
index 7c5938527..bfc4f1126 100644
--- a/src/Common/Version.php
+++ b/src/Common/Version.php
@@ -22,10 +22,8 @@ final class Version{
 	 * Enable version auto detection
 	 *
 	 * @see \chillerlan\QRCode\QROptionsTrait::$version
-	 *
-	 * @var int
 	 */
-	public const AUTO = -1;
+	public const int AUTO = -1;
 
 	/**
 	 * ISO/IEC 18004:2000 Annex E, Table E.1 - Row/column coordinates of center module of Alignment Patterns
@@ -34,7 +32,7 @@ final class Version{
 	 *
 	 * @var int[][]
 	 */
-	private const ALIGNMENT_PATTERN = [
+	private const array ALIGNMENT_PATTERN = [
 		1  => [],
 		2  => [6, 18],
 		3  => [6, 22],
@@ -84,7 +82,7 @@ final class Version{
 	 *
 	 * @var int[]
 	 */
-	private const VERSION_PATTERN = [
+	private const array VERSION_PATTERN = [
 		7  => 0b000111110010010100,
 		8  => 0b001000010110111100,
 		9  => 0b001001101010011001,
@@ -126,7 +124,7 @@ final class Version{
 	 *
 	 * @see http://www.thonky.com/qr-code-tutorial/error-correction-table
 	 */
-	private const RSBLOCKS = [
+	private const array RSBLOCKS = [
 		1  => [[ 7, [[ 1,  19], [ 0,   0]]], [10, [[ 1, 16], [ 0,  0]]], [13, [[ 1, 13], [ 0,  0]]], [17, [[ 1,  9], [ 0,  0]]]],
 		2  => [[10, [[ 1,  34], [ 0,   0]]], [16, [[ 1, 28], [ 0,  0]]], [22, [[ 1, 22], [ 0,  0]]], [28, [[ 1, 16], [ 0,  0]]]],
 		3  => [[15, [[ 1,  55], [ 0,   0]]], [26, [[ 1, 44], [ 0,  0]]], [18, [[ 2, 17], [ 0,  0]]], [22, [[ 2, 13], [ 0,  0]]]],
@@ -172,7 +170,7 @@ final class Version{
 	/**
 	 * ISO/IEC 18004:2000 Table 1 - Data capacity of all versions of QR Code
 	 */
-	private const TOTAL_CODEWORDS = [
+	private const array TOTAL_CODEWORDS = [
 		1  => 26,
 		2  => 44,
 		3  => 70,
diff --git a/src/Data/AlphaNum.php b/src/Data/AlphaNum.php
index e3d355427..2edb1df77 100644
--- a/src/Data/AlphaNum.php
+++ b/src/Data/AlphaNum.php
@@ -24,12 +24,10 @@ final class AlphaNum extends QRDataModeAbstract{
 
 	/**
 	 * ISO/IEC 18004:2000 Table 5
-	 *
-	 * @var string
 	 */
-	private const CHAR_MAP = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:';
+	private const string CHAR_MAP = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:';
 
-	public const DATAMODE = Mode::ALPHANUM;
+	public const int DATAMODE = Mode::ALPHANUM;
 
 	public function getLengthInBits():int{
 		return (int)ceil($this->getCharCount() * (11 / 2));
diff --git a/src/Data/Byte.php b/src/Data/Byte.php
index 69f7279d1..354824aa3 100644
--- a/src/Data/Byte.php
+++ b/src/Data/Byte.php
@@ -22,7 +22,7 @@ use function chr, ord;
  */
 final class Byte extends QRDataModeAbstract{
 
-	public const DATAMODE = Mode::BYTE;
+	public const int DATAMODE = Mode::BYTE;
 
 	public function getLengthInBits():int{
 		return ($this->getCharCount() * 8);
diff --git a/src/Data/ECI.php b/src/Data/ECI.php
index 34f96e547..bac131dac 100644
--- a/src/Data/ECI.php
+++ b/src/Data/ECI.php
@@ -23,7 +23,7 @@ use function mb_convert_encoding, mb_detect_encoding, mb_internal_encoding, spri
  */
 final class ECI extends QRDataModeAbstract{
 
-	public const DATAMODE = Mode::ECI;
+	public const int DATAMODE = Mode::ECI;
 
 	/**
 	 * The current ECI encoding id (default to UTF-8)
diff --git a/src/Data/Hanzi.php b/src/Data/Hanzi.php
index 48d19429a..b1f9bf899 100644
--- a/src/Data/Hanzi.php
+++ b/src/Data/Hanzi.php
@@ -32,19 +32,15 @@ final class Hanzi extends QRDataModeAbstract{
 
 	/**
 	 * possible values: GB2312, GB18030
-	 *
-	 * @var string
 	 */
-	public const ENCODING = 'GB18030';
+	public const string ENCODING = 'GB18030';
 
 	/**
 	 * @todo: other subsets???
-	 *
-	 * @var int
 	 */
-	public const GB2312_SUBSET = 0b0001;
+	public const int GB2312_SUBSET = 0b0001;
 
-	public const DATAMODE = Mode::HANZI;
+	public const int DATAMODE = Mode::HANZI;
 
 	protected function getCharCount():int{
 		return mb_strlen($this->data, self::ENCODING);
diff --git a/src/Data/Kanji.php b/src/Data/Kanji.php
index 1e657b342..8ba9d20c1 100644
--- a/src/Data/Kanji.php
+++ b/src/Data/Kanji.php
@@ -32,12 +32,10 @@ final class Kanji extends QRDataModeAbstract{
 	 * possible values: SJIS, SJIS-2004
 	 *
 	 * SJIS-2004 may produce errors in PHP < 8
-	 *
-	 * @var string
 	 */
-	public const ENCODING = 'SJIS';
+	public const string ENCODING = 'SJIS';
 
-	public const DATAMODE = Mode::KANJI;
+	public const int DATAMODE = Mode::KANJI;
 
 	protected function getCharCount():int{
 		return mb_strlen($this->data, self::ENCODING);
diff --git a/src/Data/Number.php b/src/Data/Number.php
index dda98494b..08a8dcd29 100644
--- a/src/Data/Number.php
+++ b/src/Data/Number.php
@@ -22,7 +22,7 @@ use function ceil, intdiv, preg_match, substr, unpack;
  */
 final class Number extends QRDataModeAbstract{
 
-	public const DATAMODE = Mode::NUMBER;
+	public const int DATAMODE = Mode::NUMBER;
 
 	public function getLengthInBits():int{
 		return (int)ceil($this->getCharCount() * (10 / 3));
diff --git a/src/Data/QRDataModeInterface.php b/src/Data/QRDataModeInterface.php
index 0f9f38598..07508fb71 100644
--- a/src/Data/QRDataModeInterface.php
+++ b/src/Data/QRDataModeInterface.php
@@ -23,10 +23,9 @@ interface QRDataModeInterface{
 	 *
 	 * Note: do not call this constant from the interface, but rather from one of the child classes
 	 *
-	 * @var int
 	 * @see \chillerlan\QRCode\Common\Mode
 	 */
-	public const DATAMODE = -1;
+	public const int DATAMODE = -1;
 
 	/**
 	 * retruns the length in bits of the data string
diff --git a/src/Data/QRMatrix.php b/src/Data/QRMatrix.php
index e338d8208..160e8af08 100755
--- a/src/Data/QRMatrix.php
+++ b/src/Data/QRMatrix.php
@@ -22,73 +22,41 @@ use function array_fill, array_map, array_reverse, count, intdiv;
  */
 class QRMatrix{
 
-	/*
-	 * special values
-	 */
+	/* special values */
 
-	/** @var int */
-	public const IS_DARK            = 0b100000000000;
-	/** @var int */
-	public const M_NULL             = 0b000000000000;
-	/** @var int */
-	public const M_LOGO             = 0b001000000000;
-	/** @var int */
-	public const M_LOGO_DARK        = 0b101000000000;
+	final public const int IS_DARK            = 0b100000000000;
+	final public const int M_NULL             = 0b000000000000;
+	final public const int M_LOGO             = 0b001000000000;
+	final public const int M_LOGO_DARK        = 0b101000000000;
 
-	/*
-	 * light values
-	 */
+	/* light values */
 
-	/** @var int */
-	public const M_DATA             = 0b000000000010;
-	/** @var int */
-	public const M_FINDER           = 0b000000000100;
-	/** @var int */
-	public const M_SEPARATOR        = 0b000000001000;
-	/** @var int */
-	public const M_ALIGNMENT        = 0b000000010000;
-	/** @var int */
-	public const M_TIMING           = 0b000000100000;
-	/** @var int */
-	public const M_FORMAT           = 0b000001000000;
-	/** @var int */
-	public const M_VERSION          = 0b000010000000;
-	/** @var int */
-	public const M_QUIETZONE        = 0b000100000000;
+	final public const int M_DATA             = 0b000000000010;
+	final public const int M_FINDER           = 0b000000000100;
+	final public const int M_SEPARATOR        = 0b000000001000;
+	final public const int M_ALIGNMENT        = 0b000000010000;
+	final public const int M_TIMING           = 0b000000100000;
+	final public const int M_FORMAT           = 0b000001000000;
+	final public const int M_VERSION          = 0b000010000000;
+	final public const int M_QUIETZONE        = 0b000100000000;
 
-	/*
-	 * dark values
-	 */
+	/* dark values */
 
-	/** @var int */
-	public const M_DARKMODULE       = 0b100000000001;
-	/** @var int */
-	public const M_DATA_DARK        = 0b100000000010;
-	/** @var int */
-	public const M_FINDER_DARK      = 0b100000000100;
-	/** @var int */
-	public const M_ALIGNMENT_DARK   = 0b100000010000;
-	/** @var int */
-	public const M_TIMING_DARK      = 0b100000100000;
-	/** @var int */
-	public const M_FORMAT_DARK      = 0b100001000000;
-	/** @var int */
-	public const M_VERSION_DARK     = 0b100010000000;
-	/** @var int */
-	public const M_FINDER_DOT       = 0b110000000000;
+	final public const int M_DARKMODULE       = 0b100000000001;
+	final public const int M_DATA_DARK        = 0b100000000010;
+	final public const int M_FINDER_DARK      = 0b100000000100;
+	final public const int M_ALIGNMENT_DARK   = 0b100000010000;
+	final public const int M_TIMING_DARK      = 0b100000100000;
+	final public const int M_FORMAT_DARK      = 0b100001000000;
+	final public const int M_VERSION_DARK     = 0b100010000000;
+	final public const int M_FINDER_DOT       = 0b110000000000;
 
-	/*
-	 * values used for reversed reflectance
-	 */
+	/* values used for reversed reflectance */
 
-	/** @var int */
-	public const M_DARKMODULE_LIGHT = 0b000000000001;
-	/** @var int */
-	public const M_FINDER_DOT_LIGHT = 0b010000000000;
-	/** @var int */
-	public const M_SEPARATOR_DARK   = 0b100000001000;
-	/** @var int */
-	public const M_QUIETZONE_DARK   = 0b100100000000;
+	final public const int M_DARKMODULE_LIGHT = 0b000000000001;
+	final public const int M_FINDER_DOT_LIGHT = 0b010000000000;
+	final public const int M_SEPARATOR_DARK   = 0b100000001000;
+	final public const int M_QUIETZONE_DARK   = 0b100100000000;
 
 	/**
 	 * Map of flag => coord
@@ -97,7 +65,7 @@ class QRMatrix{
 	 *
 	 * @var int[][]
 	 */
-	protected const neighbours = [
+	final protected const array neighbours = [
 		0b00000001 => [-1, -1],
 		0b00000010 => [ 0, -1],
 		0b00000100 => [ 1, -1],
diff --git a/src/Decoder/Binarizer.php b/src/Decoder/Binarizer.php
index c035cdded..48ec9ff3f 100644
--- a/src/Decoder/Binarizer.php
+++ b/src/Decoder/Binarizer.php
@@ -37,15 +37,15 @@ final class Binarizer{
 
 	// This class uses 5x5 blocks to compute local luminance, where each block is 8x8 pixels.
 	// So this is the smallest dimension in each axis we can accept.
-	private const BLOCK_SIZE_POWER  = 3;
-	private const BLOCK_SIZE        = 8;  // ...0100...00
-	private const BLOCK_SIZE_MASK   = 7;  // ...0011...11
-	private const MINIMUM_DIMENSION = 40;
-	private const MIN_DYNAMIC_RANGE = 24;
+	private const int BLOCK_SIZE_POWER  = 3;
+	private const int BLOCK_SIZE        = 8;  // ...0100...00
+	private const int BLOCK_SIZE_MASK   = 7;  // ...0011...11
+	private const int MINIMUM_DIMENSION = 40;
+	private const int MIN_DYNAMIC_RANGE = 24;
 
-#	private const LUMINANCE_BITS    = 5;
-	private const LUMINANCE_SHIFT   = 3;
-	private const LUMINANCE_BUCKETS = 32;
+#	private const int LUMINANCE_BITS    = 5;
+	private const int LUMINANCE_SHIFT   = 3;
+	private const int LUMINANCE_BUCKETS = 32;
 
 	private LuminanceSourceInterface $source;
 	/** @var int[] */
diff --git a/src/Decoder/BitMatrix.php b/src/Decoder/BitMatrix.php
index c1072f859..b262bbbf4 100644
--- a/src/Decoder/BitMatrix.php
+++ b/src/Decoder/BitMatrix.php
@@ -27,7 +27,7 @@ final class BitMatrix extends QRMatrix{
 	 *
 	 * [data bits, sequence after masking]
 	 */
-	private const DECODE_LOOKUP = [
+	private const array DECODE_LOOKUP = [
 		0x5412, // 0101010000010010
 		0x5125, // 0101000100100101
 		0x5E7C, // 0101111001111100
@@ -62,7 +62,7 @@ final class BitMatrix extends QRMatrix{
 		0x2BED, // 0010101111101101
 	];
 
-	private const FORMAT_INFO_MASK_QR = 0x5412; // 0101010000010010
+	private const int FORMAT_INFO_MASK_QR = 0x5412; // 0101010000010010
 
 	/**
 	 * This flag has effect only on the copyVersionBit() method.
diff --git a/src/Detector/FinderPatternFinder.php b/src/Detector/FinderPatternFinder.php
index 222f9e5ca..ca594ee83 100644
--- a/src/Detector/FinderPatternFinder.php
+++ b/src/Detector/FinderPatternFinder.php
@@ -26,11 +26,11 @@ use const PHP_FLOAT_MAX;
  */
 final class FinderPatternFinder{
 
-	private const MIN_SKIP      = 2;
-	private const MAX_MODULES   = 177; // 1 pixel/module times 3 modules/center
-	private const CENTER_QUORUM = 2; // support up to version 10 for mobile clients
+	private const int MIN_SKIP      = 2;
+	private const int MAX_MODULES   = 177; // 1 pixel/module times 3 modules/center
+	private const int CENTER_QUORUM = 2; // support up to version 10 for mobile clients
 	/** @var int[] */
-	private const crossCheckStateCount = [0, 0, 0, 0, 0];
+	private const array crossCheckStateCount = [0, 0, 0, 0, 0];
 	private BitMatrix $matrix;
 	/** @var \chillerlan\QRCode\Detector\FinderPattern[] */
 	private array $possibleCenters;
diff --git a/src/Output/QREps.php b/src/Output/QREps.php
index 5a6cf5885..6d418086d 100644
--- a/src/Output/QREps.php
+++ b/src/Output/QREps.php
@@ -23,7 +23,7 @@ use function array_values, count, date, implode, is_array, is_numeric, max, min,
  */
 class QREps extends QROutputAbstract{
 
-	final public const MIME_TYPE = 'application/postscript';
+	final public const string MIME_TYPE = 'application/postscript';
 
 	public static function moduleValueIsValid(mixed $value):bool{
 
diff --git a/src/Output/QRFpdf.php b/src/Output/QRFpdf.php
index 23438952a..8ee105cb3 100644
--- a/src/Output/QRFpdf.php
+++ b/src/Output/QRFpdf.php
@@ -28,7 +28,7 @@ use function class_exists;
 class QRFpdf extends QROutputAbstract{
 	use RGBArrayModuleValueTrait;
 
-	final public const MIME_TYPE = 'application/pdf';
+	final public const string MIME_TYPE = 'application/pdf';
 
 	/** @var int[]|null  */
 	protected array|null $prevColor = null;
diff --git a/src/Output/QRGdImageAVIF.php b/src/Output/QRGdImageAVIF.php
index d002ec72a..8b9db3d24 100644
--- a/src/Output/QRGdImageAVIF.php
+++ b/src/Output/QRGdImageAVIF.php
@@ -22,7 +22,7 @@ use function imageavif;
  */
 class QRGdImageAVIF extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/avif';
+	final public const string MIME_TYPE = 'image/avif';
 
 	/**
 	 * @throws \chillerlan\QRCode\Output\QRCodeOutputException
diff --git a/src/Output/QRGdImageBMP.php b/src/Output/QRGdImageBMP.php
index d3110b37f..abea060a8 100644
--- a/src/Output/QRGdImageBMP.php
+++ b/src/Output/QRGdImageBMP.php
@@ -22,7 +22,7 @@ use function imagebmp;
  */
 class QRGdImageBMP extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/bmp';
+	final public const string MIME_TYPE = 'image/bmp';
 
 	/**
 	 * @throws \chillerlan\QRCode\Output\QRCodeOutputException
diff --git a/src/Output/QRGdImageGIF.php b/src/Output/QRGdImageGIF.php
index 574d9d0b6..e210f7b68 100644
--- a/src/Output/QRGdImageGIF.php
+++ b/src/Output/QRGdImageGIF.php
@@ -22,7 +22,7 @@ use function imagegif;
  */
 class QRGdImageGIF extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/gif';
+	final public const string MIME_TYPE = 'image/gif';
 
 	/**
 	 * @throws \chillerlan\QRCode\Output\QRCodeOutputException
diff --git a/src/Output/QRGdImageJPEG.php b/src/Output/QRGdImageJPEG.php
index f6f40b34b..b1b0cceee 100644
--- a/src/Output/QRGdImageJPEG.php
+++ b/src/Output/QRGdImageJPEG.php
@@ -22,7 +22,7 @@ use function imagejpeg;
  */
 class QRGdImageJPEG extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/jpg';
+	final public const string MIME_TYPE = 'image/jpg';
 
 	protected function setTransparencyColor():int{
 		// noop - transparency is not supported
diff --git a/src/Output/QRGdImagePNG.php b/src/Output/QRGdImagePNG.php
index 73ebeb114..7f1bdc54a 100644
--- a/src/Output/QRGdImagePNG.php
+++ b/src/Output/QRGdImagePNG.php
@@ -22,7 +22,7 @@ use function imagepng, max, min;
  */
 class QRGdImagePNG extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/png';
+	final public const string MIME_TYPE = 'image/png';
 
 	protected function getQuality():int{
 		return max(-1, min(9, $this->options->quality));
diff --git a/src/Output/QRGdImageWEBP.php b/src/Output/QRGdImageWEBP.php
index 995bead18..1ce802841 100644
--- a/src/Output/QRGdImageWEBP.php
+++ b/src/Output/QRGdImageWEBP.php
@@ -22,7 +22,7 @@ use function imagewebp;
  */
 class QRGdImageWEBP extends QRGdImage{
 
-	final public const MIME_TYPE = 'image/webp';
+	final public const string MIME_TYPE = 'image/webp';
 
 	/**
 	 * @throws \chillerlan\QRCode\Output\QRCodeOutputException
diff --git a/src/Output/QRMarkupHTML.php b/src/Output/QRMarkupHTML.php
index f12e77886..11a0d2058 100644
--- a/src/Output/QRMarkupHTML.php
+++ b/src/Output/QRMarkupHTML.php
@@ -18,7 +18,7 @@ use function implode, sprintf;
  */
 class QRMarkupHTML extends QRMarkup{
 
-	final public const MIME_TYPE = 'text/html';
+	final public const string MIME_TYPE = 'text/html';
 
 	protected function createMarkup(bool $saveToFile):string{
 		$rows     = [];
diff --git a/src/Output/QRMarkupSVG.php b/src/Output/QRMarkupSVG.php
index 37b734d17..217776824 100644
--- a/src/Output/QRMarkupSVG.php
+++ b/src/Output/QRMarkupSVG.php
@@ -26,7 +26,7 @@ use function array_chunk, implode, is_string, preg_match, sprintf, trim;
  */
 class QRMarkupSVG extends QRMarkup{
 
-	final public const MIME_TYPE = 'image/svg+xml';
+	final public const string MIME_TYPE = 'image/svg+xml';
 
 	/**
 	 * @todo: XSS proof
diff --git a/src/Output/QRMarkupXML.php b/src/Output/QRMarkupXML.php
index 6d78a2a8e..1e946dd97 100644
--- a/src/Output/QRMarkupXML.php
+++ b/src/Output/QRMarkupXML.php
@@ -22,8 +22,8 @@ use function sprintf;
  */
 class QRMarkupXML extends QRMarkup{
 
-	final public const MIME_TYPE = 'application/xml';
-	final public const SCHEMA    = 'https://raw.githubusercontent.com/chillerlan/php-qrcode/main/src/Output/qrcode.schema.xsd';
+	final public const string MIME_TYPE = 'application/xml';
+	final public const string SCHEMA    = 'https://raw.githubusercontent.com/chillerlan/php-qrcode/main/src/Output/qrcode.schema.xsd';
 
 	protected DOMDocument $dom;
 
diff --git a/src/Output/QROutputInterface.php b/src/Output/QROutputInterface.php
index 44d68225b..ebd156405 100644
--- a/src/Output/QROutputInterface.php
+++ b/src/Output/QROutputInterface.php
@@ -24,7 +24,7 @@ interface QROutputInterface{
 	 * @var string[]
 	 * @see https://github.com/chillerlan/php-qrcode/issues/223
 	 */
-	public const MODES = [
+	final public const array MODES = [
 		QREps::class,
 		QRFpdf::class,
 		QRGdImageAVIF::class,
@@ -47,7 +47,7 @@ interface QROutputInterface{
 	 *
 	 * @var bool[]
 	 */
-	public const DEFAULT_MODULE_VALUES = [
+	final public const array DEFAULT_MODULE_VALUES = [
 		// light
 		QRMatrix::M_NULL             => false,
 		QRMatrix::M_DARKMODULE_LIGHT => false,
@@ -80,7 +80,7 @@ interface QROutputInterface{
 	 *
 	 * @var string[]
 	 */
-	public const LAYERNAMES = [
+	final public const array LAYERNAMES = [
 		// light
 		QRMatrix::M_NULL             => 'null',
 		QRMatrix::M_DARKMODULE_LIGHT => 'darkmodule-light',
@@ -114,7 +114,7 @@ interface QROutputInterface{
 	 * @var string
 	 * @see \chillerlan\QRCode\Output\QROutputAbstract::toBase64DataURI()
 	 */
-	public const MIME_TYPE = '';
+	public const string MIME_TYPE = '';
 
 	/**
 	 * Determines whether the given value is valid
diff --git a/src/Output/QRStringJSON.php b/src/Output/QRStringJSON.php
index a0274ef03..1803531d7 100644
--- a/src/Output/QRStringJSON.php
+++ b/src/Output/QRStringJSON.php
@@ -26,8 +26,8 @@ use function json_encode;
 class QRStringJSON extends QROutputAbstract{
 	use CssColorModuleValueTrait;
 
-	final public const MIME_TYPE = 'application/json';
-	final public const SCHEMA    = 'https://raw.githubusercontent.com/chillerlan/php-qrcode/main/src/Output/qrcode.schema.json';
+	final public const string MIME_TYPE = 'application/json';
+	final public const string SCHEMA    = 'https://raw.githubusercontent.com/chillerlan/php-qrcode/main/src/Output/qrcode.schema.json';
 
 	/**
 	 * @inheritDoc
diff --git a/src/Output/QRStringText.php b/src/Output/QRStringText.php
index d8e244d01..af2d99c7a 100644
--- a/src/Output/QRStringText.php
+++ b/src/Output/QRStringText.php
@@ -18,7 +18,7 @@ use function array_map, implode, is_string, max, min, sprintf;
  */
 class QRStringText extends QROutputAbstract{
 
-	final public const MIME_TYPE = 'text/plain';
+	final public const string MIME_TYPE = 'text/plain';
 
 	public static function moduleValueIsValid(mixed $value):bool{
 		return is_string($value);
diff --git a/tests/Data/AlphaNumTest.php b/tests/Data/AlphaNumTest.php
index 43296510a..a3d30544e 100644
--- a/tests/Data/AlphaNumTest.php
+++ b/tests/Data/AlphaNumTest.php
@@ -18,7 +18,7 @@ use chillerlan\QRCode\Data\{AlphaNum, QRDataModeInterface};
  */
 final class AlphaNumTest extends DataInterfaceTestAbstract{
 
-	protected const testData = '0 $%*+-./:';
+	protected const string testData = '0 $%*+-./:';
 
 	protected static function getDataModeInterface(string $data):QRDataModeInterface{
 		return new AlphaNum($data);
diff --git a/tests/Data/ByteTest.php b/tests/Data/ByteTest.php
index fc4d8a663..f6649dfac 100644
--- a/tests/Data/ByteTest.php
+++ b/tests/Data/ByteTest.php
@@ -19,7 +19,7 @@ use PHPUnit\Framework\Attributes\Test;
  */
 final class ByteTest extends DataInterfaceTestAbstract{
 
-	protected const testData = '[¯\_(ツ)_/¯]';
+	protected const string testData = '[¯\_(ツ)_/¯]';
 
 	protected static function getDataModeInterface(string $data):QRDataModeInterface{
 		return new Byte($data);
diff --git a/tests/Data/DataInterfaceTestAbstract.php b/tests/Data/DataInterfaceTestAbstract.php
index ab73471b5..4af387dbd 100644
--- a/tests/Data/DataInterfaceTestAbstract.php
+++ b/tests/Data/DataInterfaceTestAbstract.php
@@ -30,7 +30,7 @@ abstract class DataInterfaceTestAbstract extends TestCase{
 	protected QRData              $QRData;
 	protected QRDataModeInterface $dataMode;
 
-	protected const testData = '';
+	protected const string testData = '';
 
 	protected function setUp():void{
 		$this->QRData   = new QRData(new QROptions);
diff --git a/tests/Data/ECITest.php b/tests/Data/ECITest.php
index 2a5711986..366508b65 100644
--- a/tests/Data/ECITest.php
+++ b/tests/Data/ECITest.php
@@ -25,7 +25,7 @@ final class ECITest extends TestCase{
 	private QRData $QRData;
 	private int    $testCharset = ECICharset::GB18030;
 
-	private const testData = '无可奈何燃花作香';
+	private const string testData = '无可奈何燃花作香';
 
 	protected function setUp():void{
 		$this->QRData = new QRData(new QROptions);
diff --git a/tests/Data/HanziTest.php b/tests/Data/HanziTest.php
index b034ed83f..dd9229a00 100644
--- a/tests/Data/HanziTest.php
+++ b/tests/Data/HanziTest.php
@@ -21,7 +21,7 @@ use function bin2hex, chr, defined, sprintf;
  */
 final class HanziTest extends DataInterfaceTestAbstract{
 
-	protected const testData = '无可奈何燃花作香';
+	protected const string testData = '无可奈何燃花作香';
 
 	protected static function getDataModeInterface(string $data):QRDataModeInterface{
 		return new Hanzi($data);
diff --git a/tests/Data/KanjiTest.php b/tests/Data/KanjiTest.php
index 4771daa22..d7ad84c33 100644
--- a/tests/Data/KanjiTest.php
+++ b/tests/Data/KanjiTest.php
@@ -21,7 +21,7 @@ use function bin2hex, chr, defined, sprintf;
  */
 final class KanjiTest extends DataInterfaceTestAbstract{
 
-	protected const testData = '漂う花の香り';
+	protected const string testData = '漂う花の香り';
 
 	protected static function getDataModeInterface(string $data):QRDataModeInterface{
 		return new Kanji($data);
diff --git a/tests/Data/NumberTest.php b/tests/Data/NumberTest.php
index abfa66116..3d9dc7b82 100644
--- a/tests/Data/NumberTest.php
+++ b/tests/Data/NumberTest.php
@@ -18,7 +18,7 @@ use chillerlan\QRCode\Data\{Number, QRDataModeInterface};
  */
 final class NumberTest extends DataInterfaceTestAbstract{
 
-	protected const testData = '0123456789';
+	protected const string testData = '0123456789';
 
 	protected static function getDataModeInterface(string $data):QRDataModeInterface{
 		return new Number($data);
diff --git a/tests/Data/QRMatrixTest.php b/tests/Data/QRMatrixTest.php
index 2f5d997dc..09c81d577 100755
--- a/tests/Data/QRMatrixTest.php
+++ b/tests/Data/QRMatrixTest.php
@@ -25,7 +25,7 @@ use Generator;
 final class QRMatrixTest extends TestCase{
 	use QRMatrixDebugTrait;
 
-	private const version = 40;
+	private const int version = 40;
 	private QRMatrix $matrix;
 
 	/**
diff --git a/tests/Output/QROutputTestAbstract.php b/tests/Output/QROutputTestAbstract.php
index 8b85a4d49..f326afb88 100644
--- a/tests/Output/QROutputTestAbstract.php
+++ b/tests/Output/QROutputTestAbstract.php
@@ -31,7 +31,7 @@ abstract class QROutputTestAbstract extends TestCase{
 	protected QROutputInterface                    $outputInterface;
 	protected QRMatrix                             $matrix;
 
-	protected const buildDir = 'output-test';
+	protected const string buildDir = 'output-test';
 
 	/**
 	 * Attempts to create a directory under /.build and instances several required objects
diff --git a/tests/QRCodeReaderTestAbstract.php b/tests/QRCodeReaderTestAbstract.php
index 16995e0a6..bd299a2b4 100644
--- a/tests/QRCodeReaderTestAbstract.php
+++ b/tests/QRCodeReaderTestAbstract.php
@@ -32,7 +32,7 @@ abstract class QRCodeReaderTestAbstract extends TestCase{
 	use QRMaxLengthTrait, QRMatrixDebugTrait;
 
 	/** @see https://www.bobrosslipsum.com/ */
-	protected const loremipsum = 'Just let this happen. We just let this flow right out of our minds. '
+	final protected const string loremipsum = 'Just let this happen. We just let this flow right out of our minds. '
 		.'Anyone can paint. We touch the canvas, the canvas takes what it wants. From all of us here, '
 		.'I want to wish you happy painting and God bless, my friends. A tree cannot be straight if it has a crooked trunk. '
 		.'You have to make almighty decisions when you\'re the creator. I guess that would be considered a UFO. '
@@ -40,7 +40,7 @@ abstract class QRCodeReaderTestAbstract extends TestCase{
 		.'They say everything looks better with odd numbers of things. But sometimes I put even numbers—just '
 		.'to upset the critics. We\'ll lay all these little funky little things in there. ';
 
-	protected const samplesDir = __DIR__.'/samples/';
+	protected const string samplesDir = __DIR__.'/samples/';
 
 	protected SettingsContainerInterface|QROptions $options;
 
diff --git a/tests/QRCodeTest.php b/tests/QRCodeTest.php
index 5b3e3cb74..67ba9de42 100755
--- a/tests/QRCodeTest.php
+++ b/tests/QRCodeTest.php
@@ -28,7 +28,7 @@ final class QRCodeTest extends TestCase{
 	private QRCode    $qrcode;
 	private QROptions $options;
 
-	private const buildDir = 'output-test';
+	private const string buildDir = 'output-test';
 
 	/**
 	 * invoke test instances
diff --git a/tests/Traits/BuildDirTrait.php b/tests/Traits/BuildDirTrait.php
index ba6b59b67..efc66d14f 100644
--- a/tests/Traits/BuildDirTrait.php
+++ b/tests/Traits/BuildDirTrait.php
@@ -19,7 +19,7 @@ use function dirname, file_exists, file_get_contents, is_file, mkdir, realpath,
  */
 trait BuildDirTrait{
 
-	protected const _buildDir = __DIR__.'/../../.build/';
+	protected const string _buildDir = __DIR__.'/../../.build/';
 
 	/**
 	 * returns the full raw path to the build dir
diff --git a/tests/Traits/QRMaxLengthTrait.php b/tests/Traits/QRMaxLengthTrait.php
index 05a79e11c..5db20f2dd 100644
--- a/tests/Traits/QRMaxLengthTrait.php
+++ b/tests/Traits/QRMaxLengthTrait.php
@@ -26,7 +26,7 @@ trait QRMaxLengthTrait{
 	 *
 	 * @var int[][][]
 	 */
-	protected const MAX_LENGTH = [
+	final protected const array MAX_LENGTH = [
 	//	v  => [NUMERIC => [L, M, Q, H ], ALPHANUM => [L, M, Q, H], BINARY => [L, M, Q, H  ], KANJI => [L, M, Q, H   ]]
 		1  => [[  41,   34,   27,   17], [  25,   20,   16,   10], [  17,   14,   11,    7], [  10,    8,    7,    4]],
 		2  => [[  77,   63,   48,   34], [  47,   38,   29,   20], [  32,   26,   20,   14], [  20,   16,   12,    8]],