diff --git a/cpfcnpj.go b/cpfcnpj.go
index a49b5c0..d4032af 100644
--- a/cpfcnpj.go
+++ b/cpfcnpj.go
@@ -1,17 +1,17 @@
 package brdoc
 
 import (
+	"bytes"
 	"regexp"
 	"strconv"
+	"unicode"
 )
 
 // "Cadastro" will be used internally to define both CPF and CNPJ.
 
 var (
 	cpfRegexp  = regexp.MustCompile(`^\d{3}\.?\d{3}\.?\d{3}-?\d{2}$`)
-	cnpjRegexp = regexp.MustCompile(
-		`^\d{2}\.?\d{3}\.?\d{3}\/?(:?\d{3}[1-9]|\d{2}[1-9]\d|\d[1-9]\d{2}|[1-9]\d{3})-?\d{2}$`,
-	)
+	cnpjRegexp = regexp.MustCompile(`^[0-9A-Z]{2}\.?[0-9A-Z]{3}\.?[0-9A-Z]{3}/?[0-9A-Z]{4}-?[0-9]{2}$`)
 )
 
 // IsCPF verifies if the given string is a valid CPF document.
@@ -46,7 +46,7 @@ func isCadastro(
 		return false
 	}
 
-	cleanNonDigits(&doc)
+	cleanCadastro(&doc)
 
 	// Invalidates documents with all digits equal.
 	if allEq(doc) {
@@ -81,3 +81,14 @@ func calcCadastroDigit(doc string, position int) string {
 
 	return strconv.Itoa(11 - sum)
 }
+
+func cleanCadastro(doc *string) {
+	buf := bytes.NewBufferString("")
+	for _, r := range *doc {
+		if unicode.IsDigit(r) || unicode.IsLetter(r) {
+			buf.WriteRune(r)
+		}
+	}
+
+	*doc = buf.String()
+}
diff --git a/cpfcnpj_test.go b/cpfcnpj_test.go
index 5169f89..8a523c5 100644
--- a/cpfcnpj_test.go
+++ b/cpfcnpj_test.go
@@ -32,6 +32,8 @@ func TestIsCPF(t *testing.T) {
 		{"InvalidFormat", "099-075-865.60", false},
 
 		{"Valid", "248.438.034-80", true},
+		{"Valid", "099.075.865-60", true},
+		{"Valid", "24843803480", true},
 		{"Valid", "09907586560", true},
 	} {
 		t.Run(testName(i, tc.name), func(t *testing.T) {
@@ -63,12 +65,25 @@ func TestIsCNPJ(t *testing.T) {
 
 		{"InvalidDigits", "26.637.142/0001-85", false},
 		{"InvalidDigits", "74.221.325/0001-03", false},
+		{"InvalidDigits", "WE.0PP.M5F/0001-92", false},
 
 		{"InvalidFormat", "26-637-142.0001/58", false},
 		{"InvalidFormat", "74-221-325.0001/30", false},
 
 		{"Valid", "26.637.142/0001-58", true},
+		{"Valid", "74.221.325/0001-30", true},
+		{"Valid", "19.JA2.KO8/Z001-51", true},
+		{"Valid", "SC.RCN.1NI/0001-30", true},
+		{"Valid", "4Y.2OP.G99/0001-41", true},
+		{"Valid", "WE.0PP.M4F/0001-91", true},
+		{"Valid", "12.ABC.345/01DE-35", true},
+		{"Valid", "26637142000158", true},
 		{"Valid", "74221325000130", true},
+		{"Valid", "19JA2KO8Z00151", true},
+		{"Valid", "SCRCN1NI000130", true},
+		{"Valid", "4Y2OPG99000141", true},
+		{"Valid", "WE0PPM4F000191", true},
+		{"Valid", "12ABC34501DE35", true},
 	} {
 		t.Run(testName(i, tc.name), func(t *testing.T) {
 			assertEq(t, tc.valid, IsCNPJ(tc.doc))