diff --git a/src/main.rs b/src/main.rs
index 839d626..68e703a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,7 +55,7 @@ fn build_services(server: &Server, proxy_config: &ProxyConfig) -> Vec<Box<dyn Se
         let listen_address = format!("0.0.0.0:{}", group.port);
         let host_config_map = build_host_config_map(group);
         let lookup_dns = group.lookup_dns.unwrap_or(false);
-        
+
         log::info!("Listen at: {}, tls: {}, lookup_dns: {}", listen_address, group.tls.is_some(), lookup_dns);
 
         match &group.tls {
diff --git a/src/service.rs b/src/service.rs
index 33468f9..238abf5 100644
--- a/src/service.rs
+++ b/src/service.rs
@@ -103,10 +103,10 @@ pub fn proxy_service_tls(
     let proxy_app = ProxyApp::new(true, lookup_dns, host_config_map);
     let mut service = http_proxy_service(server_conf, proxy_app);
 
-    let cb = Box::new(Callback::new(proxy_tls).unwrap_or_else(|e| {
+    let callback = Box::new(Callback::new(proxy_tls).unwrap_or_else(|e| {
         panic!("Init SSL callback failed: {}", e);
     }));
-    let tls_settings = TlsSettings::with_callbacks(cb).unwrap_or_else(|e| {
+    let tls_settings = TlsSettings::with_callbacks(callback).unwrap_or_else(|e| {
         panic!("Init SSL settings failed: {}", e);
     });
     service.add_tls_with_settings(listen_addr, None, tls_settings);