diff --git a/lib/sni-callback.js b/lib/sni-callback.js
index 8396006..fcfb3c4 100644
--- a/lib/sni-callback.js
+++ b/lib/sni-callback.js
@@ -126,6 +126,11 @@ module.exports.create = function (opts) {
     if (opts.debug) {
       console.debug("[LEX] '" + hostname + "' is not registered, requesting approval");
     }
+    
+    if (!hostname) {
+      sniCb(new Error('[registerCert] no hostname'));
+      return;
+    }
 
     opts.approveRegistration(hostname, function (err, args) {
 
@@ -157,6 +162,11 @@ module.exports.create = function (opts) {
   }
 
   function fetch(hostname, sniCb) {
+    if (!hostname) {
+      sniCb(new Error('[sniCallback] [fetch] no hostname'));
+      return;
+    }
+    
     opts.letsencrypt.fetch({ domains: [hostname] }, function (err, certInfo) {
       if (opts.debug) {
         console.debug("[LEX] fetch from disk result '" + hostname + "':");
@@ -184,7 +194,10 @@ module.exports.create = function (opts) {
     var now = Date.now();
     var certInfo = ipc[hostname];
 
-
+    if (!hostname) {
+      cb(new Error('[sniCallback] no hostname'));
+      return;
+    }
 
     //
     // No cert is available in cache.