diff --git a/.gitignore b/.gitignore
index 3c3629e..18eb894 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 node_modules
+/nbproject/
\ No newline at end of file
diff --git a/lib/cas.js b/lib/cas.js
index 3a49580..02fec3e 100644
--- a/lib/cas.js
+++ b/lib/cas.js
@@ -374,9 +374,10 @@ CAS.prototype.validate = function(ticket, callback, service, renew)
     pgtURL = this.pgt_url;
     if (ticket.indexOf('PT-') == 0) {
       validate_path = 'proxyValidate';
+    } else if (ticket.indexOf('ST-') == 0) {
+      validate_path = 'serviceValidate';
     } else {
-      //validate_path = 'serviceValidate';
-      validate_path = 'proxyValidate';
+      throw new Error('can not determine validate path based on ticket prefix.');
     }
   }