diff --git a/src/servers/protocol/tls.rs b/src/servers/protocol/tls.rs
index 1227c15..73ace78 100644
--- a/src/servers/protocol/tls.rs
+++ b/src/servers/protocol/tls.rs
@@ -99,6 +99,6 @@ mod tests {
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         ];
         let sni = get_sni(&BUF);
-        assert!(sni[0] == "www.lirui.tech".to_string());
+        assert!(sni[0] == *"www.lirui.tech");
     }
 }
diff --git a/src/servers/upstream_address.rs b/src/servers/upstream_address.rs
index 5b07e04..0e24124 100644
--- a/src/servers/upstream_address.rs
+++ b/src/servers/upstream_address.rs
@@ -37,7 +37,7 @@ impl UpstreamAddress {
     }
 
     fn is_resolved(&self) -> bool {
-        self.resolved_addresses.len() > 0
+        !self.resolved_addresses.is_empty()
     }
 
     fn time_remaining(&self) -> Duration {