diff --git a/server.go b/server.go
index 9be8c94..ccce477 100644
--- a/server.go
+++ b/server.go
@@ -109,9 +109,35 @@ func welcomeHandler(w http.ResponseWriter, r *http.Request) {
 var tls = flagx.String("tls", "", "")
 var portptr = flagx.Int("port", 80, "")
 
+func isTlsEnabled(fileout ...*string) bool {
+	if len(*tls) == 0 {
+		return false
+	}
+
+	crtfile := *tls + ".crt"
+	if _, err := os.Stat(crtfile); os.IsNotExist(err) {
+		return false
+	}
+
+	keyfile := *tls + ".key"
+	if _, err := os.Stat(keyfile); os.IsNotExist(err) {
+		return false
+	}
+
+	if len(fileout) > 0 {
+		*fileout[0] = crtfile
+	}
+
+	if len(fileout) > 1 {
+		*fileout[1] = keyfile
+	}
+
+	return true
+}
+
 // NewHTTPServer :
 func NewHTTPServerWithPort(serveMux *http.ServeMux, port int) *Server {
-	if len(*tls) > 0 && port == 80 {
+	if isTlsEnabled() && port == 80 {
 		port = 443
 	}
 	addr := fmt.Sprintf(":%d", port)
@@ -130,7 +156,7 @@ func NewHTTPServerWithPort(serveMux *http.ServeMux, port int) *Server {
 func NewHTTPServer(serveMux *http.ServeMux) *Server {
 
 	// 시작시 자동으로 enable됨
-	if len(*tls) > 0 && *portptr == 80 {
+	if isTlsEnabled() && *portptr == 80 {
 		*portptr = 443
 	}
 	return NewHTTPServerWithPort(serveMux, *portptr)
@@ -198,12 +224,13 @@ func (server *Server) Start() error {
 		defer proxyListener.Close()
 
 		var err error
-		if len(*tls) > 0 {
-			crtfile := *tls + ".crt"
-			keyfile := *tls + ".key"
+		var crtfile string
+		var keyfile string
+		if isTlsEnabled(&crtfile, &keyfile) {
 			logger.Println("tls enabled :", crtfile, keyfile)
 			err = server.httpserver.ServeTLS(proxyListener, crtfile, keyfile)
 		} else {
+			logger.Println("tls disabled")
 			err = server.httpserver.Serve(proxyListener)
 		}