diff --git a/internal/tui/form_arp.go b/internal/tui/form_arp.go
index 5cdd40c..c4dccf1 100644
--- a/internal/tui/form_arp.go
+++ b/internal/tui/form_arp.go
@@ -106,7 +106,7 @@ func (t *tui) arpForm(sendFn func(*packemon.EthernetFrame) error, ethernetHeader
 			if count < 3 {
 				return true
 			} else if count == 3 {
-				ip, err := strIPToBytes(textToCheck)
+				ip, err := packemon.StrIPToBytes(textToCheck)
 				if err != nil {
 					return false
 				}
@@ -137,7 +137,7 @@ func (t *tui) arpForm(sendFn func(*packemon.EthernetFrame) error, ethernetHeader
 			if count < 3 {
 				return true
 			} else if count == 3 {
-				ip, err := strIPToBytes(textToCheck)
+				ip, err := packemon.StrIPToBytes(textToCheck)
 				if err != nil {
 					return false
 				}
diff --git a/networkinterface.go b/networkinterface.go
index da09d2f..d1b827e 100644
--- a/networkinterface.go
+++ b/networkinterface.go
@@ -32,7 +32,7 @@ func NewNetworkInterface(nwInterface string) (*NetworkInterface, error) {
 		return nil, errors.New("network interface may not have IP address configured")
 	}
 
-	ipAddr, err := strIPToBytes(strings.Split(ipAddrs[0].String(), "/")[0])
+	ipAddr, err := StrIPToBytes(strings.Split(ipAddrs[0].String(), "/")[0])
 	if err != nil {
 		return nil, err
 	}
diff --git a/util.go b/util.go
index f3432d9..82c4883 100644
--- a/util.go
+++ b/util.go
@@ -19,6 +19,7 @@ func WriteUint32(buf *bytes.Buffer, target uint32) {
 	buf.Write(b)
 }
 
+// stringのIPv4アドレスをbytesに変換
 func StrIPToBytes(s string) ([]byte, error) {
 	b := make([]byte, 4)
 	src := strings.Split(s, ".")
@@ -78,24 +79,6 @@ func StrIntToUint16(s string) (uint16, error) {
 	return uint16(n), nil
 }
 
-// stringのIPv4アドレスをbytesに変換
-func strIPToBytes(s string) ([]byte, error) {
-	b := make([]byte, 4)
-	src := strings.Split(s, ".")
-
-	for i := range src {
-		if len(src[i]) == 0 {
-			continue
-		}
-		ip, err := strconv.ParseUint(src[i], 10, 8)
-		if err != nil {
-			return nil, err
-		}
-		b[i] = byte(ip)
-	}
-	return b, nil
-}
-
 // copy of https://github.com/sat0ken/go-curo/blob/main/utils.go#L18
 func calculateChecksum(packet []byte) []byte {
 	// まず16ビット毎に足す