diff --git a/src/Validation/BrValidation.php b/src/Validation/BrValidation.php
index de83870..0564139 100644
--- a/src/Validation/BrValidation.php
+++ b/src/Validation/BrValidation.php
@@ -114,26 +114,26 @@ public static function cpf(string $check): bool
      */
     public static function cnpj(string $check): bool
     {
-        $check = trim($check);
+        $check = mb_strtoupper(trim($check));
         // sometimes the user submits a masked CNPJ
-        if (preg_match('/^\d\d.\d\d\d.\d\d\d\/\d\d\d\d\-\d\d/', $check)) {
+        if (preg_match('/^([A-Z0-9]{2}).([A-Z0-9]{3}).([A-Z0-9]{3})\/([A-Z0-9]{4})\-\d\d/', $check)) {
             $check = str_replace(['-', '.', '/'], '', $check);
-        } elseif (!ctype_digit($check)) {
+        } elseif (!ctype_alnum($check)) {
             return false;
         }
-
-        if (strlen($check) !== 14) {
+        $charVal = fn(int $key) => ord($check[$key]) - 48;
+        if (mb_strlen($check) !== 14) {
             return false;
         }
-        $firstSum = ((int)$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);
+        $firstSum = ($charVal(0) * 5) + ($charVal(1) * 4) + ($charVal(2) * 3) + ($charVal(3) * 2) +
+            ($charVal(4) * 9) + ($charVal(5) * 8) + ($charVal(6) * 7) + ($charVal(7) * 6) +
+            ($charVal(8) * 5) + ($charVal(9) * 4) + ($charVal(10) * 3) + ($charVal(11) * 2);
 
         $firstVerificationDigit = $firstSum % 11 < 2 ? 0 : 11 - ($firstSum % 11);
 
-        $secondSum = ((int)$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) +
+        $secondSum = ($charVal(0) * 6) + ($charVal(1) * 5) + ($charVal(2) * 4) + ($charVal(3) * 3) +
+            ($charVal(4) * 2) + ($charVal(5) * 9) + ($charVal(6) * 8) + ($charVal(7) * 7) +
+            ($charVal(8) * 6) + ($charVal(9) * 5) + ($charVal(10) * 4) + ($charVal(11) * 3) +
             ((int)$check[12] * 2);
 
         $secondVerificationDigit = $secondSum % 11 < 2 ? 0 : 11 - ($secondSum % 11);
diff --git a/tests/TestCase/Validation/BrValidationTest.php b/tests/TestCase/Validation/BrValidationTest.php
index 2eec0dd..9d06d5f 100644
--- a/tests/TestCase/Validation/BrValidationTest.php
+++ b/tests/TestCase/Validation/BrValidationTest.php
@@ -125,6 +125,19 @@ public function testSsn()
         $this->assertTrue(BrValidation::personId('04.295.166/0001-33'));
         $this->assertTrue(BrValidation::personId('33.530.486/0001-29'));
 
+        //Testing alphanumeric CNPJ
+        $this->assertFalse(BrValidation::cnpj('ABC123Z4000110'));
+        $this->assertFalse(BrValidation::cnpj('9AB5B5FF0001AB'));
+        $this->assertFalse(BrValidation::cnpj('9AB5B5FF0001AB'));//Last two chars must be numeric
+        $this->assertFalse(BrValidation::cnpj('12.@BC.345/01#E-35'));//bad chars @#
+        $this->assertFalse(BrValidation::cnpj('XOX&@!B0K000156'));//Bad chars &@!
+
+        $this->assertTrue(BrValidation::cnpj('XOXDNB0K000156'));
+        $this->assertTrue(BrValidation::cnpj('F9Z3AJUJ000108'));
+        $this->assertTrue(BrValidation::cnpj('f9z3AjUj000108'));//lowercase must work
+        $this->assertTrue(BrValidation::cnpj('NGZ9C1T4000145'));
+        $this->assertTrue(BrValidation::cnpj('12.ABC.345/01DE-35'));
+
         // Testing ssn
         $this->assertFalse(BrValidation::personId('04295165000133'));
         $this->assertFalse(BrValidation::personId('33530485000129'));
@@ -134,10 +147,13 @@ public function testSsn()
         $this->assertFalse(BrValidation::personId('33.530.485/0001-29'));
         $this->assertFalse(BrValidation::personId('04.295.166/0001-01'));
         $this->assertFalse(BrValidation::personId('33.530.486/0001-30'));
+        $this->assertFalse(BrValidation::personId('ABC123Z4000110'));
         $this->assertTrue(BrValidation::personId('04295166000133'));
         $this->assertTrue(BrValidation::personId('33530486000129'));
         $this->assertTrue(BrValidation::personId('04.295.166/0001-33'));
         $this->assertTrue(BrValidation::personId('33.530.486/0001-29'));
+        $this->assertTrue(BrValidation::personId('NGZ9C1T4000145'));
+        $this->assertTrue(BrValidation::personId('12.ABC.345/01DE-35'));
 
         // Testing invalid input
         $this->assertFalse(BrValidation::personId('3712093712890371289073901287390812'));