diff --git a/common/rfb/SecurityServer.cxx b/common/rfb/SecurityServer.cxx
index 76ece77..5bd7b2c 100644
--- a/common/rfb/SecurityServer.cxx
+++ b/common/rfb/SecurityServer.cxx
@@ -37,7 +37,11 @@
 
 StringParameter SecurityServer::secTypes
 ("SecurityTypes",
- "Specify which security scheme to use (None, VncAuth)",
+ "Specify which security scheme to use (None, VncAuth, Plain"
+#ifdef HAVE_GNUTLS
+ ", TLSNone, TLSVnc, TLSPlain, X509None, X509Vnc, X509Plain"
+#endif
+ ")",
 #ifdef HAVE_GNUTLS
  "VncAuth,TLSVnc",
 #else