diff --git a/credit_card.go b/credit_card.go
index c7dd659..fad719b 100644
--- a/credit_card.go
+++ b/credit_card.go
@@ -17,17 +17,17 @@ const (
 )
 
 var creditCards = map[string]creditCard{
-	"VISA":             {"VISA", 16, []int{4539, 4556, 4916, 4532, 4929, 40240071, 4485, 4716, 4}},
-	"MasterCard":       {"MasterCard", 16, []int{51, 52, 53, 54, 55}},
-	"American Express": {"American Express", 15, []int{34, 37}},
-	"Discover":         {"Discover", 16, []int{6011}},
+	"visa":             {"VISA", 16, []int{4539, 4556, 4916, 4532, 4929, 40240071, 4485, 4716, 4}},
+	"mastercard":       {"MasterCard", 16, []int{51, 52, 53, 54, 55}},
+	"american express": {"American Express", 15, []int{34, 37}},
+	"discover":         {"Discover", 16, []int{6011}},
 }
 
 // CreditCardType returns one of the following credit values:
 // VISA, MasterCard, American Express and Discover
 var cacheCreditCard string
 
-func CreditCardType() string {
+func creditCardType() string {
 	n := len(creditCards)
 	r := rand.New(src)
 	if cacheCreditCard != "" {
@@ -43,15 +43,15 @@ func CreditCardType() string {
 }
 
 // CreditCardNum generated credit card number according to the card number rules
-func CreditCardNum(ccType string) string {
+func creditCardNum(ccType string) string {
 	r := rand.New(src)
 	if ccType != "" {
 		ccType = strings.ToLower(ccType)
+		cacheCreditCard = ccType
 	} else if cacheCreditCard != "" {
-		ccType = cacheCreditCard
+		ccType = strings.ToLower(cacheCreditCard)
 	} else {
-
-		ccType = strings.ToLower(CreditCardType())
+		ccType = strings.ToLower(creditCardType())
 		cacheCreditCard = ccType
 	}
 	card := creditCards[ccType]
diff --git a/faker.go b/faker.go
index bcea43f..e41cc79 100644
--- a/faker.go
+++ b/faker.go
@@ -214,11 +214,11 @@ func userDefinedString(v reflect.Value, tag string) error {
 		val = ipv6()
 	case CREDIT_CARD_NUMBER:
 
-		val = CreditCardNum("")
+		val = creditCardNum("")
 
 	case CREDIT_CARD_TYPE:
 
-		val = CreditCardType()
+		val = creditCardType()
 
 	}
 	v.SetString(val)
diff --git a/faker_test.go b/faker_test.go
index f9a309e..d74c273 100644
--- a/faker_test.go
+++ b/faker_test.go
@@ -55,8 +55,8 @@ type CStruct struct {
 type TaggedStruct struct {
 	Latitude         float32 `faker:"lat"`
 	Long             float32 `faker:"long"`
-	CreditCardType   string  `faker:"cc_type"`
 	CreditCardNumber string  `faker:"cc_number"`
+	CreditCardType   string  `faker:"cc_type"`
 	Email            string  `faker:"email"`
 	IPV4             string  `faker:"ipv4"`
 	IPV6             string  `faker:"ipv6"`