diff --git a/email.go b/email.go
index 4459824..1d1fb53 100644
--- a/email.go
+++ b/email.go
@@ -16,7 +16,7 @@ const ResultNotEmail = "NOT_EMAIL"
 const ipV6Prefix = "[IPv6:"
 
 // notQuotedChars is the valid not quoted characters.
-var notQuotedChars = regexp.MustCompile("[a-zA-Z0-9!#$%&'*+-/=?^_`{|}~]")
+var notQuotedChars = regexp.MustCompile("[a-zA-Z0-9!#$%&'*\\+\\-/=?^_`{|}~]")
 
 // IsEmail checks if the given string is an email address.
 func IsEmail(email string) Result {
@@ -33,7 +33,7 @@ func IsEmail(email string) Result {
 	user := email[:atIndex]
 
 	// Cannot be empty user
-	if len(user) == 0 || len(user) > 64 {
+	if user == "" || len(user) > 64 {
 		return ResultNotEmail
 	}
 
diff --git a/fqdn.go b/fqdn.go
index 1112dc0..4ba200e 100644
--- a/fqdn.go
+++ b/fqdn.go
@@ -13,7 +13,7 @@ const CheckerFqdn = "fqdn"
 const ResultNotFqdn = "NOT_FQDN"
 
 // Valid characters excluding full-width characters.
-var fqdnValidChars = regexp.MustCompile("^[a-z0-9\u00a1-\uff00\uff06-\uffff-]+$")
+var fqdnValidChars = regexp.MustCompile("^[a-z0-9\u00a1-\uff00\uff06-\uffff\\-]+$")
 
 // IsFqdn checks if the given string is a fully qualified domain name.
 func IsFqdn(domain string) Result {