diff --git a/nmap-service-probes b/nmap-service-probes
index 5861f1174..817565843 100644
--- a/nmap-service-probes
+++ b/nmap-service-probes
@@ -1267,6 +1267,8 @@ match securepath m|^GENERAL: \d+ \d+<EoM>\n$| p/HP StorageWorks SecurePath/ o/Wi
 match securepath m|^Unauthorized client; connection refused<EoM>\n| p/HP StorageWorks SecurePath/ i/unauthorized/ o/Windows/
 match service-monitor m|^\0\0\0\x18\0\0..\0\0..\xff\xff\xff\xff\xff\xff\xff\xff\0\0\0\x02\0\0\0\0\0\0\0\x15spectrum\0spectrum\0\0\0\0| p/CA Spectrum/
 
+match slnp m|^220 SLNP (\w+)@[vV]ersion:[\s]?V?([^@]+)@((user:[^@]+@)?pid:[\d]+)\n$| p/Sisis $1/ v/$2/ i/$3/ o/Unix/
+
 # good SMTP banner regexps can be found here:
 # http://www.tty1.net/smtp-survey/measurement_en.html