diff --git a/crates/shadowsocks-service/src/acl/mod.rs b/crates/shadowsocks-service/src/acl/mod.rs
index 92713ed2..2f120333 100644
--- a/crates/shadowsocks-service/src/acl/mod.rs
+++ b/crates/shadowsocks-service/src/acl/mod.rs
@@ -543,7 +543,7 @@ impl AccessControl {
 
     /// Returns the ASCII representation a domain name,
     /// if conversion fails returns original string
-    fn convert_to_ascii(host: &str) -> Cow<str> {
+    fn convert_to_ascii(host: &str) -> Cow<'_, str> {
         idna::domain_to_ascii(host)
             .map(From::from)
             .unwrap_or_else(|_| host.into())