diff --git a/gin.go b/gin.go
index 1633fe13..18afdb51 100644
--- a/gin.go
+++ b/gin.go
@@ -17,6 +17,7 @@ import (
 
 	"github.com/gin-gonic/gin/internal/bytesconv"
 	"github.com/gin-gonic/gin/render"
+	"github.com/gin-gonic/gin/utils"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/h2c"
 )
@@ -401,24 +402,17 @@ func (engine *Engine) Run(addr ...string) (err error) {
 }
 
 func (engine *Engine) prepareTrustedCIDRs() ([]*net.IPNet, error) {
+	var err error
 	if engine.trustedProxies == nil {
 		return nil, nil
 	}
 
 	cidr := make([]*net.IPNet, 0, len(engine.trustedProxies))
 	for _, trustedProxy := range engine.trustedProxies {
-		if !strings.Contains(trustedProxy, "/") {
-			ip := parseIP(trustedProxy)
-			if ip == nil {
-				return cidr, &net.ParseError{Type: "IP address", Text: trustedProxy}
-			}
-
-			switch len(ip) {
-			case net.IPv4len:
-				trustedProxy += "/32"
-			case net.IPv6len:
-				trustedProxy += "/128"
-			}
+		trustedProxy, err = utils.MakeTrustIP(trustedProxy)	
+		
+		if err != nil {
+			return cidr, err
 		}
 		_, cidrNet, err := net.ParseCIDR(trustedProxy)
 		if err != nil {
@@ -489,20 +483,6 @@ func (engine *Engine) validateHeader(header string) (clientIP string, valid bool
 	return "", false
 }
 
-// parseIP parse a string representation of an IP and returns a net.IP with the
-// minimum byte representation or nil if input is invalid.
-func parseIP(ip string) net.IP {
-	parsedIP := net.ParseIP(ip)
-
-	if ipv4 := parsedIP.To4(); ipv4 != nil {
-		// return ip in a 4-byte representation
-		return ipv4
-	}
-
-	// return ip in a 16-byte representation or nil
-	return parsedIP
-}
-
 // RunTLS attaches the router to a http.Server and starts listening and serving HTTPS (secure) requests.
 // It is a shortcut for http.ListenAndServeTLS(addr, certFile, keyFile, router)
 // Note: this method will block the calling goroutine indefinitely unless an error happens.
diff --git a/utils/ip.go b/utils/ip.go
new file mode 100644
index 00000000..9f4d54b9
--- /dev/null
+++ b/utils/ip.go
@@ -0,0 +1,46 @@
+package utils
+
+import (
+	"net"
+	"strings"
+)
+
+func parseIP(ip string) (net.IP, error) {
+	parsedIP := net.ParseIP(ip)
+
+	if ipv4 := parsedIP.To4(); ipv4 != nil {
+		return ipv4, nil
+	}
+	if parsedIP != nil{
+		return parsedIP, nil
+	}
+	return nil, &net.ParseError{Type: "IP address", Text: ip}
+}
+
+func MakeTrustIP(trustedIP string) (string, error) {
+	if strings.Contains(trustedIP, "/") {
+		return trustedIP, nil	
+	}
+	ip, err := parseIP(trustedIP)
+
+	if err != nil {
+		return "", err
+	}
+	
+	var mapRenderIP = map [int]func(trustIP string) string{
+		net.IPv4len: func(trustIP string) string{
+			return trustIP + "/32"
+		},
+		net.IPv6len: func(trustIP string) string{
+			return trustIP + "/32"
+		},
+	}
+
+	fn, isExistKey := mapRenderIP[len(ip)]
+
+	if isExistKey != true{
+		return "", &net.ParseError{Type: "IP address", Text: trustedIP}
+	}
+
+	return fn(trustedIP), nil
+}
\ No newline at end of file