diff --git a/phpstan.neon b/phpstan.neon
index 2a03e49..2d588bc 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,5 +1,5 @@
 parameters:
-	level: 1
+	level: 6
 	treatPhpDocTypesAsCertain: false
 	bootstrapFiles:
 		- tests/bootstrap.php
diff --git a/src/Validation/BrValidation.php b/src/Validation/BrValidation.php
index 5bc0873..28ccd52 100644
--- a/src/Validation/BrValidation.php
+++ b/src/Validation/BrValidation.php
@@ -96,12 +96,12 @@ public static function cpf(string $check): bool
             $sum = 0;
             $position = $pos + 1;
             for ($i = 0; $i <= $pos - 1; $i++, $position--) {
-                $sum += (int)$check[$i] * $position;
+                $sum += (int)(int)$check[$i] * $position;
             }
             $div = $sum % 11;
-            $check[$pos] = $div < 2 ? 0 : 11 - $div;
+            (int)$check[$pos] = $div < 2 ? 0 : 11 - $div;
         }
-        $dvRight = (int)$check[9] * 10 + (int)$check[10];
+        $dvRight = (int)(int)$check[9] * 10 + (int)(int)$check[10];
 
         return $dvRight == $dv;
     }
@@ -125,20 +125,20 @@ public static function cnpj(string $check): bool
         if (strlen($check) !== 14) {
             return false;
         }
-        $firstSum = ($check[0] * 5) + ($check[1] * 4) + ($check[2] * 3) + ($check[3] * 2) +
-            ($check[4] * 9) + ($check[5] * 8) + ($check[6] * 7) + ($check[7] * 6) +
-            ($check[8] * 5) + ($check[9] * 4) + ($check[10] * 3) + ($check[11] * 2);
+        $firstSum = ((int)$check[0] * 5) + ((int)$check[1] * 4) + ((int)$check[2] * 3) + ((int)$check[3] * 2) +
+            ((int)$check[4] * 9) + ((int)$check[5] * 8) + ((int)$check[6] * 7) + ((int)$check[7] * 6) +
+            ((int)$check[8] * 5) + ((int)$check[9] * 4) + ((int)$check[10] * 3) + ((int)$check[11] * 2);
 
         $firstVerificationDigit = $firstSum % 11 < 2 ? 0 : 11 - ($firstSum % 11);
 
-        $secondSum = ($check[0] * 6) + ($check[1] * 5) + ($check[2] * 4) + ($check[3] * 3) +
-            ($check[4] * 2) + ($check[5] * 9) + ($check[6] * 8) + ($check[7] * 7) +
-            ($check[8] * 6) + ($check[9] * 5) + ($check[10] * 4) + ($check[11] * 3) +
-            ($check[12] * 2);
+        $secondSum = ((int)$check[0] * 6) + ((int)$check[1] * 5) + ((int)$check[2] * 4) + ((int)$check[3] * 3) +
+            ((int)$check[4] * 2) + ((int)$check[5] * 9) + ((int)$check[6] * 8) + ((int)$check[7] * 7) +
+            ((int)$check[8] * 6) + ((int)$check[9] * 5) + ((int)$check[10] * 4) + ((int)$check[11] * 3) +
+            ((int)$check[12] * 2);
 
         $secondVerificationDigit = $secondSum % 11 < 2 ? 0 : 11 - ($secondSum % 11);
 
-        return ($check[12] == $firstVerificationDigit) && ($check[13] == $secondVerificationDigit);
+        return ((int)$check[12] == $firstVerificationDigit) && ((int)$check[13] == $secondVerificationDigit);
     }
 
     /**
@@ -162,7 +162,7 @@ public static function cnh(string $cnh): bool
         }
         // Calculate the number
         for ($i = 0, $j = 9, $v = 0; $i < 9; ++$i, --$j) {
-            $v += $check[$i] * $j;
+            $v += (int)$check[$i] * $j;
         }
 
         $dsc = 0;
@@ -174,7 +174,7 @@ public static function cnh(string $cnh): bool
         }
 
         for ($i = 0, $j = 1, $v = 0; $i < 9; ++$i, ++$j) {
-            $v += $check[$i] * $j;
+            $v += (int)$check[$i] * $j;
         }
 
         // Calculate second digit
@@ -198,7 +198,7 @@ public static function cns(string $cns): bool
             $len = strlen($cns);
             $soma = 0;
             for ($i = 0; $i < $len; $i++) {
-                $soma += $cns[$i] * (15 - $i);
+                $soma += (int)$cns[$i] * (15 - $i);
             }
 
             return $soma % 11 === 0;
diff --git a/src/Validation/EsValidation.php b/src/Validation/EsValidation.php
index be7523a..015e2a0 100644
--- a/src/Validation/EsValidation.php
+++ b/src/Validation/EsValidation.php
@@ -131,14 +131,14 @@ public static function nif(string $check): bool
             return false;
         }
 
-        $sum = $check[2] + $check[4] + $check[6];
+        $sum = (int)$check[2] + (int)$check[4] + (int)$check[6];
 
         for ($i = 1; $i < 8; $i += 2) {
-            $tmp = (string)(2 * $check[$i]);
-            $sum += $tmp[0] + (strlen($tmp) === 2 ? $tmp[1] : 0);
+            $tmp = (string)(2 * (int)$check[$i]);
+            $sum += (int)$tmp[0] + (strlen($tmp) === 2 ? (int)$tmp[1] : 0);
         }
 
-        $num = 10 - substr(strval($sum), -1);
+        $num = 10 - (int)substr(strval($sum), -1);
 
         return $check[strlen($check) - 1] === chr($num + 64);
     }
diff --git a/src/Validation/FiValidation.php b/src/Validation/FiValidation.php
index c2f4f1e..49153bc 100644
--- a/src/Validation/FiValidation.php
+++ b/src/Validation/FiValidation.php
@@ -67,7 +67,7 @@ public static function phone(string $check): bool
     public static function personId(string $check): bool
     {
         $pattern = '/^\d{6}[-+A][0-9A-Z]{4}$/';
-        if (!(bool)preg_match($pattern, strval($check))) {
+        if (!preg_match($pattern, $check)) {
             return false;
         }
 
@@ -120,7 +120,7 @@ public static function businessId(string $check): bool
         $n = 0;
 
         foreach (str_split(substr($businessId, 0, 7)) as $k => $y) {
-            $n += $weights[$k] * $y;
+            $n += $weights[$k] * (int)$y;
         }
 
         $match = $n % 11 === 0 ? 0 : 11 - $n % 11;
@@ -196,12 +196,12 @@ public static function calculateReferenceNumberChecksum(string $base): int
                 $i = 0;
             }
             $multiplier = $pattern[$i];
-            $result += $multiplier * $node;
+            $result += $multiplier * (int)$node;
             $i++;
         }
 
         $lastItems = str_split(strval($result), 1);
-        $checksum = 10 - end($lastItems);
+        $checksum = 10 - (int)end($lastItems);
 
         if ($checksum >= 10) {
             $checksum = 0;
diff --git a/src/Validation/FrValidation.php b/src/Validation/FrValidation.php
index 941fa06..464b9fc 100644
--- a/src/Validation/FrValidation.php
+++ b/src/Validation/FrValidation.php
@@ -81,13 +81,13 @@ public static function personId(string $check): bool
         // source : https://xml.insee.fr/schema/nir.html
         // check : https://www.parodie.com/monetique/nir.htm
         if ($numberWithoutKey[6] === 'A') {
-            $numberWithoutKey = str_replace('A', '0', $numberWithoutKey);
+            $numberWithoutKey = (int)str_replace('A', '0', $numberWithoutKey);
             $numberWithoutKey -= 1000000;
         } elseif ($numberWithoutKey[6] === 'B') {
-            $numberWithoutKey = str_replace('B', '0', $numberWithoutKey);
+            $numberWithoutKey = (int)str_replace('B', '0', $numberWithoutKey);
             $numberWithoutKey -= 2000000;
         }
 
-        return $key == 97 - ($numberWithoutKey - (floor($numberWithoutKey / 97) * 97));
+        return $key === (string)(97 - ((int)$numberWithoutKey - (int)(floor((int)$numberWithoutKey / 97) * 97)));
     }
 }
diff --git a/src/Validation/IrValidation.php b/src/Validation/IrValidation.php
index 6771185..f79409d 100644
--- a/src/Validation/IrValidation.php
+++ b/src/Validation/IrValidation.php
@@ -122,7 +122,7 @@ public static function personId(string $check): bool
         $sum = 0;
         $equivalent = 0;
         for ($i = 0; $i < 9; $i++) {
-            $sum += substr($check, $i, 1) * (10 - $i);
+            $sum += (int)substr($check, $i, 1) * (10 - $i);
             if (substr($check, 1, 1) === substr($check, $i, 1)) {
                 $equivalent++;
             }
diff --git a/src/Validation/LvValidation.php b/src/Validation/LvValidation.php
index ccee3ff..af92716 100644
--- a/src/Validation/LvValidation.php
+++ b/src/Validation/LvValidation.php
@@ -83,10 +83,6 @@ public static function personId(string $check): bool
             $counter += (int)$check[$index] * $multiplier;
         }
 
-        if ($counter === false) {
-            return false;
-        }
-
         return (1101 - $counter) % 11 === (int)$check[10];
     }
 }
diff --git a/src/Validation/PlValidation.php b/src/Validation/PlValidation.php
index 1903f29..021e45f 100644
--- a/src/Validation/PlValidation.php
+++ b/src/Validation/PlValidation.php
@@ -74,7 +74,7 @@ public static function nip(string $check): bool
         $weights = [6, 5, 7, 2, 3, 4, 5, 6, 7];
         $check = str_replace('-', '', $check);
         for ($i = 0; $i < 9; $i++) {
-            $sum += $check[$i] * $weights[$i];
+            $sum += (int)$check[$i] * $weights[$i];
         }
         $control = $sum % 11;
         if ($control === 10) {
@@ -99,7 +99,7 @@ public static function pesel(string $check): bool
             $sum = 0;
             $weights = [1, 3, 7, 9, 1, 3, 7, 9, 1, 3];
             for ($i = 0; $i < 10; $i++) {
-                $sum += $check[$i] * $weights[$i];
+                $sum += (int)$check[$i] * $weights[$i];
             }
             $control = 10 - $sum % 10;
             if ($control === 10) {
@@ -133,7 +133,7 @@ public static function regon(string $check): bool
         if (strlen($check) === 9) {
             // Validate short version (9 digits)
             $sum = array_sum(array_map(function ($weight, $digit) {
-                return $weight * $digit;
+                return $weight * (int)$digit;
             }, [8, 9, 2, 3, 4, 5, 6, 7], array_slice($chars, 0, 8)));
             $checksum = $sum % 11;
 
@@ -141,7 +141,7 @@ public static function regon(string $check): bool
         } else {
             // Validate long version (14 digits)
             $sum = array_sum(array_map(function ($weight, $digit) {
-                return $weight * $digit;
+                return $weight * (int)$digit;
             }, [2, 4, 8, 5, 0, 9, 7, 3, 6, 1, 2, 4, 8], array_slice($chars, 0, 13)));
             $checksum = $sum % 11;
 
diff --git a/src/Validation/RsValidation.php b/src/Validation/RsValidation.php
index b244f5a..f635c6c 100644
--- a/src/Validation/RsValidation.php
+++ b/src/Validation/RsValidation.php
@@ -59,7 +59,8 @@ public static function personId(string $check): bool
         }
 
         [$a, $b, $c, $d, $e, $f, $g, $h, $i, $j, $k, $l, $m] = str_split(strval($check));
-        $checksum = 11 - ( 7 * ($a + $g) + 6 * ($b + $h) + 5 * ($c + $i) + 4 * ($d + $j) + 3 * ($e + $k) + 2 * ($f + $l) ) % 11;
+        $checksum = 11 - ( 7 * ((int)$a + (int)$g) + 6 * ((int)$b + (int)$h)
+                + 5 * ((int)$c + (int)$i) + 4 * ((int)$d + (int)$j) + 3 * ((int)$e + (int)$k) + 2 * ((int)$f + (int)$l) ) % 11;
 
         return $checksum == $m;
     }
diff --git a/src/Validation/RuValidation.php b/src/Validation/RuValidation.php
index 5a7d60a..54b2724 100644
--- a/src/Validation/RuValidation.php
+++ b/src/Validation/RuValidation.php
@@ -106,7 +106,7 @@ public static function vatin(string $check): bool
             $checksum = array_pop($digits);
             $tbNum = [2, 4, 10, 3, 5, 9, 4, 6, 8];
             $calculatedChecksum = array_sum(array_map(function ($value, $multiplier) {
-                return $value * $multiplier;
+                return $value * (int)$multiplier;
             }, $tbNum, $digits)) % 11 % 10;
         } else {
             // human person
@@ -121,7 +121,7 @@ public static function vatin(string $check): bool
             $sum = [0, 0];
             foreach ($tbNum as $key => $multipliers) {
                 $sum[$key] = array_sum(array_map(function ($value, $multiplier) {
-                    return $value * $multiplier;
+                    return $value * (int)$multiplier;
                 }, $multipliers, $digits)) % 11 % 10;
             }
 
@@ -164,7 +164,7 @@ public static function snils(string $check): bool
 
         $sum = 0;
         foreach ($digits as $position => $value) {
-            $sum += ($position + 1) * $value;
+            $sum += ($position + 1) * (int)$value;
         }
 
         $calculatedChecksum = $sum % 101;
diff --git a/src/Validation/TrValidation.php b/src/Validation/TrValidation.php
index 140694b..24fa5a6 100644
--- a/src/Validation/TrValidation.php
+++ b/src/Validation/TrValidation.php
@@ -57,18 +57,19 @@ public static function personId(string $tckn): bool
             return false;
         }
 
-        if ($tckn[0] === 0) {
+
+        if ((int)$tckn[0] === 0) {
             return false;
         }
 
-        $even = $tckn[0] + $tckn[2] + $tckn[4] + $tckn[6] + $tckn[8];
-        $odd = $tckn[1] + $tckn[3] + $tckn[5] + $tckn[7];
+        $even = (int)$tckn[0] + (int)$tckn[2] + (int)$tckn[4] + (int)$tckn[6] + (int)$tckn[8];
+        $odd = (int)$tckn[1] + (int)$tckn[3] + (int)$tckn[5] + (int)$tckn[7];
         $check = ($even * 7) - $odd;
         if ($check % 10 !== (int)$tckn[9]) {
             return false;
         }
 
-        $check = $even + $odd + $tckn[9];
+        $check = $even + $odd + (int)$tckn[9];
         if ($check % 10 !== (int)$tckn[10]) {
             return false;
         }
diff --git a/src/Validation/TwValidation.php b/src/Validation/TwValidation.php
index 37de0fb..e22c61a 100644
--- a/src/Validation/TwValidation.php
+++ b/src/Validation/TwValidation.php
@@ -78,7 +78,7 @@ public static function personId(string $check): bool
         $checksum = (int)($n1 / 10) + ($n1 % 10) * 9;
 
         for ($i = 1; $i < 9; $i++) {
-            $checksum += $check[$i] * (9 - $i);
+            $checksum += (int)$check[$i] * (9 - $i);
         }
 
         return substr(strval(10 - ($checksum % 10)), 0, 1) === $check[9];
@@ -99,12 +99,12 @@ public static function ubn(string $check): bool
         $tbNum = [1, 2, 1, 2, 1, 2, 4, 1];
         $intSum = 0;
         for ($i = 0; $i < 8; $i++) {
-            $intMultiply = $check[$i] * $tbNum[$i];
+            $intMultiply = (int)$check[$i] * $tbNum[$i];
             $intAddition = floor($intMultiply / 10) + ($intMultiply % 10);
             $intSum += $intAddition;
         }
 
-        return ($intSum % 10 === 0) || ($intSum % 10 === 9 && $check[6] === 7);
+        return ($intSum % 10 === 0) || ($intSum % 10 === 9 && (int)$check[6] === 7);
     }
 
     /**