diff --git a/examples/smtp_selfsigned.rs b/examples/smtp_selfsigned.rs
index 9a59ac6..8cf1927 100644
--- a/examples/smtp_selfsigned.rs
+++ b/examples/smtp_selfsigned.rs
@@ -17,15 +17,16 @@ fn main() {
         .body("Be happy!")
         .unwrap();
 
+    // Use a custom certificate stored on disk to securely verify the server's certificate
     let pem_cert = fs::read("certificate.pem").unwrap();
     let cert = Certificate::from_pem(&pem_cert).unwrap();
-    let mut tls = TlsParameters::builder("smtp.server.com".into());
+    let mut tls = TlsParameters::builder("smtp.server.com".to_string());
     tls.add_root_certificate(cert);
     let tls = tls.build().unwrap();
 
     let creds = Credentials::new("smtp_username".to_string(), "smtp_password".to_string());
 
-    // Open a remote connection to gmail
+    // Open a remote connection to the smtp server
     let mailer = SmtpTransport::builder_dangerous("smtp.server.com")
         .port(465)
         .tls(Tls::Wrapper(tls))