diff --git a/lib/dgram.js b/lib/dgram.js
index d5c2e0da69c..4166b026e1b 100644
--- a/lib/dgram.js
+++ b/lib/dgram.js
@@ -237,11 +237,15 @@ Socket.prototype.setTTL = function(arg) {
 
 
 Socket.prototype.setMulticastTTL = function(arg) {
-  if (this._handle.setMulticastTTL(arg) == -1) {
+  if (typeof arg !== 'number') {
+    throw new TypeError('Argument must be a number');
+  }
+
+  if (this._handle.setMulticastTTL(arg)) {
     throw errnoException(errno, 'setMulticastTTL');
   }
 
-  return true;
+  return arg;
 };