diff --git a/deferred.coffee b/deferred.coffee
index d8dfd72..89c91d0 100644
--- a/deferred.coffee
+++ b/deferred.coffee
@@ -5,7 +5,7 @@
 # ####[Source (github)](http://github.com/sudhirj/simply-deferred) | [Documentation](https://github.com/sudhirj/simply-deferred#simply-deferred)
 # © Sudhir Jonathan [sudhirjonathan.com](http://www.sudhirjonathan.com)
 
-VERSION = '2.3.0'
+VERSION = '2.4.0'
 
 # First, let's set up the constants that we'll need to signify the state of the `deferred` object. These will be returned from the `state()` method.
 
@@ -83,16 +83,10 @@ Deferred = ->
       master = new Deferred()
 
       filter = (source, funnel, callback) ->
-        if callback?
-          candidate[source]((args...) ->
-            value = callback(args...)
-            if isPromise(value)
-              value.done(master.resolve).fail(master.reject)
-            else
-              master[funnel](value)
-          )
-        else
-          candidate[source](master[funnel])
+        if not callback then return candidate[source](master[funnel])
+        candidate[source] (args...) ->
+          value = callback(args...)
+          if isPromise(value) then value.done(master.resolve).fail(master.reject) else master[funnel](value)
 
       filter('done', 'resolve', doneFilter)
       filter('fail', 'reject', failFilter)
diff --git a/deferred.js b/deferred.js
index c02fc65..55d7be1 100644
--- a/deferred.js
+++ b/deferred.js
@@ -3,7 +3,7 @@
   var Deferred, PENDING, REJECTED, RESOLVED, VERSION, after, execute, flatten, has, installInto, isArguments, isPromise, wrap, _when,
     __slice = [].slice;
 
-  VERSION = '2.3.0';
+  VERSION = '2.4.0';
 
   PENDING = "pending";
 
@@ -106,20 +106,19 @@
         var filter, master;
         master = new Deferred();
         filter = function(source, funnel, callback) {
-          if (callback != null) {
-            return candidate[source](function() {
-              var args, value;
-              args = 1 <= arguments.length ? __slice.call(arguments, 0) : [];
-              value = callback.apply(null, args);
-              if (isPromise(value)) {
-                return value.done(master.resolve).fail(master.reject);
-              } else {
-                return master[funnel](value);
-              }
-            });
-          } else {
+          if (!callback) {
             return candidate[source](master[funnel]);
           }
+          return candidate[source](function() {
+            var args, value;
+            args = 1 <= arguments.length ? __slice.call(arguments, 0) : [];
+            value = callback.apply(null, args);
+            if (isPromise(value)) {
+              return value.done(master.resolve).fail(master.reject);
+            } else {
+              return master[funnel](value);
+            }
+          });
         };
         filter('done', 'resolve', doneFilter);
         filter('fail', 'reject', failFilter);
@@ -234,6 +233,16 @@
     };
     exports.when = _when;
     exports.installInto = installInto;
+  } else if (typeof define === 'function' && define.amd) {
+    define(function() {
+      if (Zepto) {
+        return installInto(Zepto);
+      } else {
+        return Deferred;
+      }
+    });
+  } else if (Zepto) {
+    installInto(Zepto);
   } else {
     this.Deferred = function() {
       return new Deferred();
diff --git a/deferred.min.js b/deferred.min.js
index 6240ad0..ea0a1e4 100644
--- a/deferred.min.js
+++ b/deferred.min.js
@@ -1 +1 @@
-!function(){var n,r,e,t,u,l,o,i,a,c,s,f,p,h,g=[].slice;u="2.3.0",r="pending",t="resolved",e="rejected",a=function(n,r){return null!=n?n.hasOwnProperty(r):void 0},s=function(n){return a(n,"length")&&a(n,"callee")},f=function(n){return a(n,"promise")&&"function"==typeof(null!=n?n.promise:void 0)},i=function(n){return s(n)?i(Array.prototype.slice.call(n)):Array.isArray(n)?n.reduce(function(n,r){return Array.isArray(r)?n.concat(i(r)):(n.push(r),n)},[]):[n]},l=function(n,r){return 0>=n?r():function(){return--n<1?r.apply(this,arguments):void 0}},p=function(n,r){return function(){var e;return e=[n].concat(Array.prototype.slice.call(arguments,0)),r.apply(this,e)}},o=function(n,r,e){var t,u,l,o,a;for(o=i(n),a=[],u=0,l=o.length;l>u;u++)t=o[u],a.push(t.call.apply(t,[e].concat(g.call(r))));return a},n=function(){var u,l,a,c,s,p;return p=r,c=[],s=[],a={},this.promise=function(u){var l,h;return u=u||{},u.state=function(){return p},h=function(n,e){return function(){return p===r&&e.push.apply(e,i(arguments)),n()&&o(arguments,a),u}},u.done=h(function(){return p===t},c),u.fail=h(function(){return p===e},s),u.always=function(){var n;return(n=u.done.apply(u,arguments)).fail.apply(n,arguments)},l=function(r,e){var t,l;return t=new n,l=function(n,r,e){return e?u[n](function(){var t,u;return t=1<=arguments.length?g.call(arguments,0):[],u=e.apply(null,t),f(u)?u[n](function(){var n;return n=1<=arguments.length?g.call(arguments,0):[],r.apply(null,n)}):r(u)}):u[n](function(){var n;return n=1<=arguments.length?g.call(arguments,0):[],r.apply(null,n)})},l("done",t.resolve,r),l("fail",t.reject,e),t},u.pipe=l,u.then=l,null==u.promise&&(u.promise=function(){return u}),u},this.promise(this),u=this,l=function(n,e,t){return function(){return p===r?(p=n,a=arguments,o(e,a,t),u):this}},this.resolve=l(t,c),this.reject=l(e,s),this.resolveWith=function(n,r){return l(t,c,n).apply(null,r)},this.rejectWith=function(n,r){return l(e,s,n).apply(null,r)},this},h=function(){var r,e,t,u,o,a,c;if(e=i(arguments),o=new n,!e.length)return o.resolve().promise();for(u=[],t=l(e.length,function(){return o.resolve.apply(o,u)}),e.forEach(function(n,r){return f(n)?n.done(function(){var n;return n=1<=arguments.length?g.call(arguments,0):[],u[r]=n.length>1?n:n[0],t()}):(u[r]=n,t())}),a=0,c=e.length;c>a;a++)r=e[a],f(r)&&r.fail(o.reject);return o.promise()},c=function(r){return r.Deferred=function(){return new n},r.ajax=p(r.ajax,function(r,e){var t,u,l,o;return null==e&&(e={}),u=new n,t=function(n,r){return p(n,function(){var n,e;return e=arguments[0],n=2<=arguments.length?g.call(arguments,1):[],e&&e.apply(null,n),r.apply(null,n)})},e.success=t(e.success,u.resolve),e.error=t(e.error,u.reject),o=r(e),l=u.promise(),l.abort=function(){return o.abort()},l}),r.when=h},"undefined"!=typeof exports?(exports.Deferred=function(){return new n},exports.when=h,exports.installInto=c):(this.Deferred=function(){return new n},this.Deferred.when=h,this.Deferred.installInto=c)}.call(this);
\ No newline at end of file
+!function(){var n,r,e,t,u,o,i,l,a,c,s,f,p,h,g=[].slice;u="2.4.0",r="pending",t="resolved",e="rejected",a=function(n,r){return null!=n?n.hasOwnProperty(r):void 0},s=function(n){return a(n,"length")&&a(n,"callee")},f=function(n){return a(n,"promise")&&"function"==typeof(null!=n?n.promise:void 0)},l=function(n){return s(n)?l(Array.prototype.slice.call(n)):Array.isArray(n)?n.reduce(function(n,r){return Array.isArray(r)?n.concat(l(r)):(n.push(r),n)},[]):[n]},o=function(n,r){return 0>=n?r():function(){return--n<1?r.apply(this,arguments):void 0}},p=function(n,r){return function(){var e;return e=[n].concat(Array.prototype.slice.call(arguments,0)),r.apply(this,e)}},i=function(n,r,e){var t,u,o,i,a;for(i=l(n),a=[],u=0,o=i.length;o>u;u++)t=i[u],a.push(t.call.apply(t,[e].concat(g.call(r))));return a},n=function(){var u,o,a,c,s,p;return p=r,c=[],s=[],a={},this.promise=function(u){var o,h;return u=u||{},u.state=function(){return p},h=function(n,e){return function(){return p===r&&e.push.apply(e,l(arguments)),n()&&i(arguments,a),u}},u.done=h(function(){return p===t},c),u.fail=h(function(){return p===e},s),u.always=function(){var n;return(n=u.done.apply(u,arguments)).fail.apply(n,arguments)},o=function(r,e){var t,o;return o=new n,t=function(n,r,e){return e?u[n](function(){var n,t;return n=1<=arguments.length?g.call(arguments,0):[],t=e.apply(null,n),f(t)?t.done(o.resolve).fail(o.reject):o[r](t)}):u[n](o[r])},t("done","resolve",r),t("fail","reject",e),o},u.pipe=o,u.then=o,null==u.promise&&(u.promise=function(){return u}),u},this.promise(this),u=this,o=function(n,e,t){return function(){return p===r?(p=n,a=arguments,i(e,a,t),u):this}},this.resolve=o(t,c),this.reject=o(e,s),this.resolveWith=function(n,r){return o(t,c,n).apply(null,r)},this.rejectWith=function(n,r){return o(e,s,n).apply(null,r)},this},h=function(){var r,e,t,u,i,a,c;if(e=l(arguments),1===e.length)return f(e[0])?e[0]:(new n).resolve(e[0]).promise();if(i=new n,!e.length)return i.resolve().promise();for(u=[],t=o(e.length,function(){return i.resolve.apply(i,u)}),e.forEach(function(n,r){return f(n)?n.done(function(){var n;return n=1<=arguments.length?g.call(arguments,0):[],u[r]=n.length>1?n:n[0],t()}):(u[r]=n,t())}),a=0,c=e.length;c>a;a++)r=e[a],f(r)&&r.fail(i.reject);return i.promise()},c=function(r){return r.Deferred=function(){return new n},r.ajax=p(r.ajax,function(r,e){var t,u,o,i;return null==e&&(e={}),u=new n,t=function(n,r){return p(n,function(){var n,e;return e=arguments[0],n=2<=arguments.length?g.call(arguments,1):[],e&&e.apply(null,n),r.apply(null,n)})},e.success=t(e.success,u.resolve),e.error=t(e.error,u.reject),i=r(e),o=u.promise(),o.abort=function(){return i.abort()},o}),r.when=h},"undefined"!=typeof exports?(exports.Deferred=function(){return new n},exports.when=h,exports.installInto=c):"function"==typeof define&&define.amd?define(function(){return Zepto?c(Zepto):n}):Zepto?c(Zepto):(this.Deferred=function(){return new n},this.Deferred.when=h,this.Deferred.installInto=c)}.call(this);
\ No newline at end of file
diff --git a/package.json b/package.json
index eeaf71f..e05a5f5 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "author": "Sudhir Jonathan <contact.me@sudhirjonathan.com> (http://www.sudhirjonathan.com)",
   "name": "simply-deferred",
   "description": "A deferred library for Node.js and the browser with a simplified jQuery compatible API",
-  "version": "2.3.0",
+  "version": "2.4.0",
   "homepage": "http://sudhirj.github.com/simply-deferred/",
   "repository": {
     "type": "git",