diff --git a/src/code/disassembler.js b/src/code/disassembler.js
index 68bbc6cf72..60ce1f40a3 100644
--- a/src/code/disassembler.js
+++ b/src/code/disassembler.js
@@ -7,7 +7,7 @@ var createExpressions = function (instructions) {
   var expressions = []
   var labels = 0
   for (var i = 0; i < instructions.length; i++) {
-    let expr = instructions[i]
+    var expr = instructions[i]
     expr.functional = false
     if (expr.name === 'JUMPDEST') {
       expr.label = 'label' + (++labels)
diff --git a/src/lib/eventManager.js b/src/lib/eventManager.js
index 8a5839effb..616e0f3732 100644
--- a/src/lib/eventManager.js
+++ b/src/lib/eventManager.js
@@ -2,6 +2,7 @@
 
 function eventManager () {
   this.registered = {}
+  this.anonymous = {}
 }
 
 /*
@@ -13,15 +14,16 @@ function eventManager () {
    * @param {Func} func         - function of the listenners that will be executed
 */
 eventManager.prototype.unregister = function (eventName, obj, func) {
+  if (!this.registered[eventName]) {
+    return
+  }
   if (obj instanceof Function) {
     func = obj
-    obj = {}
+    obj = this.anonymous
   }
   for (var reg in this.registered[eventName]) {
-    if (this.registered[eventName][reg] &&
-      this.registered[eventName][reg].obj === obj && (!func || this.registered[eventName][reg].func === func)) {
+    if (this.registered[eventName][reg].obj === obj && this.registered[eventName][reg].func === func) {
       this.registered[eventName].splice(reg, 1)
-      return
     }
   }
 }
@@ -40,7 +42,7 @@ eventManager.prototype.register = function (eventName, obj, func) {
   }
   if (obj instanceof Function) {
     func = obj
-    obj = {}
+    obj = this.anonymous
   }
   this.registered[eventName].push({
     obj: obj,
@@ -56,9 +58,12 @@ eventManager.prototype.register = function (eventName, obj, func) {
    * @param {Array}j - argument that will be passed to the exectued function.
 */
 eventManager.prototype.trigger = function (eventName, args) {
+  if (!this.registered[eventName]) {
+    return
+  }
   for (var listener in this.registered[eventName]) {
     var l = this.registered[eventName][listener]
-    l.func.apply(l.obj, args)
+    l.func.apply(l.obj === this.anonymous ? {} : l.obj, args)
   }
 }
 
diff --git a/src/ui/CodeListView.js b/src/ui/CodeListView.js
index 22b9ca79e3..d355dbb751 100644
--- a/src/ui/CodeListView.js
+++ b/src/ui/CodeListView.js
@@ -21,8 +21,8 @@ CodeListView.prototype.render = function () {
 
 CodeListView.prototype.init = function () {
   var self = this
-  this.codeManager.register('changed', this, this.changed)
-  this.parent.register('traceUnloaded', this, function () {
+  this.codeManager.event.register('changed', this, this.changed)
+  this.parent.event.register('traceUnloaded', this, function () {
     self.changed([], '', -1)
   })
 }
diff --git a/src/ui/StepDetail.js b/src/ui/StepDetail.js
index ab1feeaa79..ac752e5a51 100644
--- a/src/ui/StepDetail.js
+++ b/src/ui/StepDetail.js
@@ -19,17 +19,17 @@ StepDetail.prototype.render = function () {
 
 StepDetail.prototype.init = function () {
   var self = this
-  this.parent.register('traceUnloaded', this, function () {
+  this.parent.event.register('traceUnloaded', this, function () {
     self.detail = initDetail()
     self.basicPanel.update(self.detail)
   })
 
-  this.parent.register('newTraceLoaded', this, function () {
+  this.parent.event.register('newTraceLoaded', this, function () {
     self.detail = initDetail()
     self.basicPanel.update(self.detail)
   })
 
-  this.parent.register('indexChanged', this, function (index) {
+  this.parent.event.register('indexChanged', this, function (index) {
     if (index < 0) return
 
     self.detail['vm trace step'] = index
diff --git a/src/ui/TxBrowser.js b/src/ui/TxBrowser.js
index 71091f5671..b19701dfe8 100644
--- a/src/ui/TxBrowser.js
+++ b/src/ui/TxBrowser.js
@@ -74,7 +74,7 @@ TxBrowser.prototype.update = function (error, tx) {
     info.from = tx.from
     info.to = tx.to
     info.hash = tx.hash
-    this.trigger('newTraceRequested', [this.blockNumber, this.txNumber, tx])
+    this.event.trigger('newTraceRequested', [this.blockNumber, this.txNumber, tx])
   } else {
     var mes = '<not found>'
     info.from = mes
diff --git a/test/eventManager.js b/test/eventManager.js
new file mode 100644
index 0000000000..1e497504cf
--- /dev/null
+++ b/test/eventManager.js
@@ -0,0 +1,35 @@
+'use strict'
+var tape = require('tape')
+var EventManager = require('../src/lib/eventManager')
+tape('eventManager', function (t) {
+  t.test('eventManager', function (st) {
+    var events = new EventManager()
+    var listenner = {}
+
+    var trace = ''
+    listenner.listen = function (data1) {
+      trace += data1
+    }
+    var registeredFunction = function (data) {
+      trace += data
+    }
+    events.register('event1', listenner, listenner.listen)
+    events.register('event2', registeredFunction)
+    events.trigger('event1', ['event1'])
+    events.trigger('event2', ['event2'])
+    st.equal(trace, 'event1event2')
+
+    events.unregister('event1', listenner.listen)
+    st.equal(events.registered['event1'].length, 1)
+    st.equal(events.registered['event2'].length, 1)
+
+    events.unregister('event1', listenner, listenner.listen)
+    st.equal(events.registered['event1'].length, 0)
+    st.equal(events.registered['event2'].length, 1)
+
+    events.unregister('event2', registeredFunction)
+    st.equal(events.registered['event1'].length, 0)
+    st.equal(events.registered['event2'].length, 0)
+    st.end()
+  })
+})
diff --git a/test/tests.js b/test/tests.js
index 2886ff2985..38820e4fe0 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -5,3 +5,4 @@ require('./codeManager.js')
 require('./util.js')
 require('./astwalker.js')
 require('./disassembler.js')
+require('./eventManager.js')