diff --git a/lib/server.js b/lib/server.js
index 5db5ec6..ec8682d 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -174,10 +174,14 @@ function noExOpHandler(req, res, next) {
 }
 
 
-function getDTraceHander(op, cb1, cb2) {
+function getArgumentsWithDTrace(args, op, cb1, cb2) {
   assert.ok(op);
 
-  return function(req, res, next) {
+  var index = 0;
+  if (typeof(args[0]) === 'object')
+    index = 1;
+
+  args.splice(index, 0, function(req, res, next) {
     dtrace.fire(op, function() {
       var c = req.connection;
       return [
@@ -190,9 +194,10 @@ function getDTraceHander(op, cb1, cb2) {
       ];
     });
     return next();
-  };
-}
+  });
 
+  return args;
+}
 
 ///--- API
 
@@ -425,11 +430,11 @@ module.exports = Server;
  * @throws {TypeError} on bad input
  */
 Server.prototype.add = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('add',
-                               function(req, res) {
-                                 return req.attributes.length;
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'add',
+                                    function(req, res) {
+                                      return req.attributes.length;
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_ADD, name, args);
 };
@@ -446,8 +451,8 @@ Server.prototype.add = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.bind = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('bind'));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'bind');
 
   return this._mount(Protocol.LDAP_REQ_BIND, name, args);
 };
@@ -464,14 +469,14 @@ Server.prototype.bind = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.compare = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('compare',
-                               function(req, res) {
-                                 return req.attribute;
-                               },
-                               function(req, res) {
-                                 return req.value;
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'compare',
+                                    function(req, res) {
+                                      return req.attribute;
+                                    },
+                                    function(req, res) {
+                                      return req.value;
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_COMPARE, name, args);
 };
@@ -488,8 +493,8 @@ Server.prototype.compare = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.del = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('delete'));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'delete');
 
   return this._mount(Protocol.LDAP_REQ_DELETE, name, args);
 };
@@ -506,14 +511,14 @@ Server.prototype.del = function(name) {
  * @throws {TypeError} on bad input.
  */
 Server.prototype.exop = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('exop',
-                               function(req, res) {
-                                 return req.name;
-                               },
-                               function(req, res) {
-                                 return req.value;
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'exop',
+                                    function(req, res) {
+                                      return req.name;
+                                    },
+                                    function(req, res) {
+                                      return req.value;
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_EXTENSION, name, args, true);
 };
@@ -530,11 +535,11 @@ Server.prototype.exop = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.modify = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('modify',
-                               function(req, res) {
-                                 return req.changes.length;
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'modify',
+                                    function(req, res) {
+                                      return req.changes.length;
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_MODIFY, name, args);
 };
@@ -551,15 +556,15 @@ Server.prototype.modify = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.modifyDN = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('modifyDN',
-                               function(req, res) {
-                                 return req.newRdn.toString();
-                               },
-                               function(req, res) {
-                                 return (req.newSuperior ?
-                                         req.newSuperior.toString() : '');
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'modifyDN',
+                                    function(req, res) {
+                                      return req.newRdn.toString();
+                                    },
+                                    function(req, res) {
+                                      return (req.newSuperior ?
+                                              req.newSuperior.toString() : '');
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_MODRDN, name, args);
 };
@@ -576,14 +581,14 @@ Server.prototype.modifyDN = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.search = function(name) {
-  var args = Array.prototype.slice.call(arguments, 1);
-  args.unshift(getDTraceHander('search',
-                               function(req, res) {
-                                 return req.scope;
-                               },
-                               function(req, res) {
-                                 return req.filter.toString();
-                               }));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'search',
+                                    function(req, res) {
+                                      return req.scope;
+                                    },
+                                    function(req, res) {
+                                      return req.filter.toString();
+                                    });
 
   return this._mount(Protocol.LDAP_REQ_SEARCH, name, args);
 };
@@ -599,8 +604,8 @@ Server.prototype.search = function(name) {
  * @throws {TypeError} on bad input
  */
 Server.prototype.unbind = function() {
-  var args = Array.prototype.slice.call(arguments, 0);
-  args.unshift(getDTraceHander('unbind'));
+  var args = getArgumentsWithDTrace(Array.prototype.slice.call(arguments, 1),
+                                    'unbind');
 
   return this._mount(Protocol.LDAP_REQ_UNBIND, 'unbind', args, true);
 };
@@ -608,6 +613,9 @@ Server.prototype.unbind = function() {
 
 // All these just reexpose the requisite net.Server APIs
 Server.prototype.listen = function(port, host, callback) {
+  if (!port)
+    throw new TypeError('port (number) required');
+
   if (typeof(host) === 'function') {
     callback = host;
     host = '0.0.0.0';
@@ -752,6 +760,7 @@ Server.prototype._mount = function(op, name, argv, notDN) {
 
   var backend = this;
   var index = 0;
+
   if (typeof(argv[0]) === 'object' && !Array.isArray(argv[0])) {
     backend = argv[0];
     index = 1;