diff --git a/xmlout.js b/xmlout.js
index f09aed1..66ccdcb 100644
--- a/xmlout.js
+++ b/xmlout.js
@@ -177,7 +177,9 @@ function prefixMessageWithSN(data) {
     sn = '';
 
     if (data.SN && data.SN.trim()) {
-        sn = data['SN'].replace(/ /g, '-').replace(/-*/g, '-').trim();
+        sn = data['SN'].replace(/ /g, '-');
+        sn = sn.replace(/[\()]/g, '-');
+        sn = sn.replace(/-/g, '-').trim();
         return 'SN=' + sn + '; ' + data['MESSAGE'];
     }
     else if (data['MESSAGE'].search(/^SN=.+;/) == -1) {