diff --git a/net/cidr/range.go b/net/cidr/range.go
index 1d76987..3dbff65 100644
--- a/net/cidr/range.go
+++ b/net/cidr/range.go
@@ -6,12 +6,12 @@ import (
 )
 
 func NewCIDRRanger(cidr string) (CIDRRanger, error) {
-	nIP, nIPNet, err := net.ParseCIDR(cidr)
+	_, nIPNet, err := net.ParseCIDR(cidr)
 	if nil != err {
 		return nil, err
 	}
 
-	switch len(nIP) {
+	switch len(nIPNet.IP) {
 	case net.IPv4len:
 		cr := &cidrRangeIPv4{
 			cidrNet: nIPNet,