diff --git a/lib/std.js b/lib/std.js
index 294e32d..9c0c1f9 100644
--- a/lib/std.js
+++ b/lib/std.js
@@ -363,7 +363,7 @@ function StdEventTarget() {
     };
 
     this.addEventListener = function(type, listener) {
-        if (typeof f === "function") {
+        if (typeof listener === "function") {
             this.__events__.push({
                 "type": type,
                 "listener": listener,
@@ -376,7 +376,7 @@ function StdEventTarget() {
     };
 
     this.removeEventListener = function(type, listener) {
-        if (typeof f === "function") {
+        if (typeof listener === "function") {
             for (var i = 0; i < this.__events__.length; i++) {
                 var e = this.__events__[i];
                 if (e.type == event.type && typeof(e.listener) === "function" && e.listener.toString() == listener.toString()) {