diff --git a/src/Helpers/Mask.php b/src/Helpers/Mask.php
index fe81746..f607708 100644
--- a/src/Helpers/Mask.php
+++ b/src/Helpers/Mask.php
@@ -109,9 +109,15 @@ public static function cep($value)
     */
     public static function cnpj($value)
     {
-        $value = preg_replace('/\D/', '', $value);
+        $value = (string) $value;
+
+        if (preg_match('/[a-z]/', $value)) {
+            return null;
+        }
+
+        $value = preg_replace('/[^A-Z0-9]/', '', $value);
 
-        if (strlen($value) == 14) {
+        if (preg_match('/^[A-Z0-9]{12}[0-9]{2}$/', $value)) {
             return vsprintf("%s%s.%s%s%s.%s%s%s/%s%s%s%s-%s%s", str_split($value));
         }
 
diff --git a/src/Helpers/Validate.php b/src/Helpers/Validate.php
index f782a14..204d30b 100644
--- a/src/Helpers/Validate.php
+++ b/src/Helpers/Validate.php
@@ -50,34 +50,40 @@ public static function isValidCpf($cpf)
      */
     public static function isValidCnpj($cnpj)
     {
-        $cnpj = preg_replace('/[^0-9]/', '', (string) $cnpj);
+        $cnpj = (string) $cnpj;
 
-        if (strlen($cnpj) != 14) {
+        if (preg_match('/[a-z]/', $cnpj)) {
             return false;
         }
 
-        if (preg_match('/(\d)\1{13}/', $cnpj)) {
+        $cnpj = preg_replace('/[^A-Z0-9]/', '', $cnpj);
+
+        if (!preg_match('/^[A-Z0-9]{12}[0-9]{2}$/', $cnpj)) {
+            return false;
+        }
+
+        if (preg_match('/(.)\1{13}/', $cnpj)) {
             return false;
         }
 
         for ($i = 0, $j = 5, $soma = 0; $i < 12; $i++) {
-            $soma += $cnpj[$i] * $j;
+            $soma += (ord($cnpj[$i]) - 48) * $j;
             $j = ($j == 2) ? 9 : $j - 1;
         }
 
         $resto = $soma % 11;
 
-        if ($cnpj[12] != ($resto < 2 ? 0 : 11 - $resto)) {
+        if ((int) $cnpj[12] != ($resto < 2 ? 0 : 11 - $resto)) {
             return false;
         }
 
         for ($i = 0, $j = 6, $soma = 0; $i < 13; $i++) {
-            $soma += $cnpj[$i] * $j;
+            $soma += (ord($cnpj[$i]) - 48) * $j;
             $j = ($j == 2) ? 9 : $j - 1;
         }
 
         $resto = $soma % 11;
-        return $cnpj[13] == ($resto < 2 ? 0 : 11 - $resto);
+        return (int) $cnpj[13] == ($resto < 2 ? 0 : 11 - $resto);
     }
 
     /**
diff --git a/tests/Helpers/MaskTest.php b/tests/Helpers/MaskTest.php
index c359a18..9c3adac 100644
--- a/tests/Helpers/MaskTest.php
+++ b/tests/Helpers/MaskTest.php
@@ -20,10 +20,15 @@ public function testMaskBank()
     public function testeMaskCnpj()
     {
         $expected = '99.999.999/9999-99';
-
         $actual = Mask::cnpj('99999999999999');
-
         $this->assertEquals($expected, $actual);
+
+        $this->assertEquals('GC.85C.XG8/0001-89', Mask::cnpj('GC85CXG8000189'));
+        $this->assertEquals('3N.XJ6.DX8/0001-70', Mask::cnpj('3NXJ6DX8000170'));
+        $this->assertEquals('LL.APR.PG5/0001-06', Mask::cnpj('LLAPRPG5000106'));
+        $this->assertEquals('H6.HT4.V25/0001-85', Mask::cnpj('H6HT4V25000185'));
+        $this->assertEquals('G5.6R6.P3L/0001-45', Mask::cnpj('G56R6P3L000145'));
+        $this->assertNull(Mask::cnpj('gc85cxg8000189'));
     }
 
     public function testMaskCep()
diff --git a/tests/Helpers/ValidateTest.php b/tests/Helpers/ValidateTest.php
index 9abd100..18cb18e 100644
--- a/tests/Helpers/ValidateTest.php
+++ b/tests/Helpers/ValidateTest.php
@@ -55,6 +55,19 @@ public function cnpjProvider()
             ['56.396.710/0001-37', true],
             ['14528181000138', true],
             ['56.396.710/000137', true],
+            ['32.474.406/0001-00', true],
+            ['11.602.425/0001-97', true],
+            ['48.657.442/0001-31', true],
+            ['GC.85C.XG8/0001-89', true],
+            ['3N.XJ6.DX8/0001-70', true],
+            ['LL.APR.PG5/0001-06', true],
+            ['H6.HT4.V25/0001-85', true],
+            ['G5.6R6.P3L/0001-45', true],
+            ['GC85CXG8000189', true],
+            ['GC.85C.XG8/0001-80', false],
+            ['GC.85C.XG8/0001-AB', false],
+            ['gc.85c.xg8/0001-89', false],
+            ['gc85cxg8000189', false],
             ['1452818100013', false],
             ['14528181', false],
             ['145281810001383', false],
diff --git a/tests/HelpersTest.php b/tests/HelpersTest.php
index a1137e8..3675b2d 100644
--- a/tests/HelpersTest.php
+++ b/tests/HelpersTest.php
@@ -172,6 +172,7 @@ public function testMaskCnpj()
         $right = '11222333444455';
 
         $this->assertEquals(Helpers::maskCnpj($right), '11.222.333/4444-55');
+        $this->assertEquals(Helpers::maskCnpj('GC85CXG8000189'), 'GC.85C.XG8/0001-89');
         $this->assertNull(Helpers::maskCnpj($wrong));
     }