diff --git a/tls_icon.php b/tls_icon.php
index c735916..34f27ea 100644
--- a/tls_icon.php
+++ b/tls_icon.php
@@ -5,7 +5,7 @@ class tls_icon extends rcube_plugin
 	const POSTFIX_TLS_REGEX = "/\(using (TLS.*)\) \(/im";
 	const POSTFIX_LOCAL_REGEX = "/\([a-zA-Z]*, from userid [0-9]*\)/im";
 	const SENDMAIL_TLS_REGEX = "/\(version=(TLS.*)\)(\s+for|;)/im";
-	const STALWART_TLS_REGEX = "/\(using TLSv1\.(?:2|3) with cipher .+\)/im";
+	const STALWART_TLS_REGEX = "/\(using TLSv1\.[23] with cipher .+\)/im";
 
 	private $message_headers_done = false;
 	private $icon_img;