diff --git a/src/utils/helper.rs b/src/utils/helper.rs
index 6a585d1..28e64c6 100644
--- a/src/utils/helper.rs
+++ b/src/utils/helper.rs
@@ -120,7 +120,7 @@ pub fn is_multi_broadcast(ip: u32) -> bool {
     first >= 224 && first <= 239
 }
 
-pub fn ip_to_string(ip: u32) -> String {
+pub fn ip_to_string(ip: &u32) -> String {
     format!(
         "{}.{}.{}.{}",
         ((ip >> 24) & 0xff) as u8,
diff --git a/src/utils/myrsa.rs b/src/utils/myrsa.rs
index 675c7c9..95be7a7 100644
--- a/src/utils/myrsa.rs
+++ b/src/utils/myrsa.rs
@@ -147,9 +147,9 @@ mod tests {
 
     #[test]
     fn test_net_bit_to_ip() {
-        assert_eq!(ip_to_string(net_bit_len_to_mask(8)), "255.0.0.0");
-        assert_eq!(ip_to_string(net_bit_len_to_mask(16)), "255.255.0.0");
-        assert_eq!(ip_to_string(net_bit_len_to_mask(24)), "255.255.255.0");
-        assert_eq!(ip_to_string(net_bit_len_to_mask(32)), "255.255.255.255");
+        assert_eq!(ip_to_string(&net_bit_len_to_mask(8)), "255.0.0.0");
+        assert_eq!(ip_to_string(&net_bit_len_to_mask(16)), "255.255.0.0");
+        assert_eq!(ip_to_string(&net_bit_len_to_mask(24)), "255.255.255.0");
+        assert_eq!(ip_to_string(&net_bit_len_to_mask(32)), "255.255.255.255");
     }
 }