diff --git a/echo.go b/echo.go
index b1a13319..ed13e8ae 100644
--- a/echo.go
+++ b/echo.go
@@ -546,8 +546,16 @@ func (e *Echo) StartTLS(address string, certFile, keyFile string) (err error) {
 	return e.startTLS(address)
 }
 
-// StartAutoTLS starts an HTTPS server using certificates automatically from https://letsencrypt.org.
+// StartAutoTLS starts an HTTPS server using certificates automatically installed from https://letsencrypt.org.
+// Port in address must be 443.
 func (e *Echo) StartAutoTLS(address string) error {
+	_, port, err := net.SplitHostPort(address)
+	if err != nil {
+		return err
+	}
+	if port != "443" {
+		return errors.New("port for auto tls must be 443")
+	}
 	s := e.TLSServer
 	s.TLSConfig = new(tls.Config)
 	s.TLSConfig.GetCertificate = e.AutoTLSManager.GetCertificate
diff --git a/middleware/logger.go b/middleware/logger.go
index 6d3b0c5f..70278371 100644
--- a/middleware/logger.go
+++ b/middleware/logger.go
@@ -39,9 +39,9 @@ type (
 		// - latency_human (Human readable)
 		// - bytes_in (Bytes received)
 		// - bytes_out (Bytes sent)
-		// - header:<name>
-		// - query:<name>
-		// - form:<name>
+		// - header:<NAME>
+		// - query:<NAME>
+		// - form:<NAME>
 		//
 		// Example "${remote_ip} ${status}"
 		//
diff --git a/website/content/middleware/logger.md b/website/content/middleware/logger.md
index 81ff003c..564d15b5 100644
--- a/website/content/middleware/logger.md
+++ b/website/content/middleware/logger.md
@@ -64,9 +64,9 @@ LoggerConfig struct {
   // - latency_human (Human readable)
   // - bytes_in (Bytes received)
   // - bytes_out (Bytes sent)
-  // - header:<name>
-  // - query:<name>
-  // - form:<name>
+  // - header:<NAME>
+  // - query:<NAME>
+  // - form:<NAME>
   //
   // Example "${remote_ip} ${status}"
   //