diff --git a/core/src/components/nav/test/nav-controller.spec.ts b/core/src/components/nav/test/nav-controller.spec.ts
index cf9c3773e8..875e01600a 100644
--- a/core/src/components/nav/test/nav-controller.spec.ts
+++ b/core/src/components/nav/test/nav-controller.spec.ts
@@ -5,6 +5,7 @@ import { AnimationControllerImpl } from '../../animation-controller/animation-co
 import { createConfigController } from '../../../global/config-controller';
 
 import { NavDirection, NavOptions, ViewState } from '../nav-util';
+import { MyCustomEvent, mockLifecycle } from '../transition';
 
 
 describe('NavController', () => {
@@ -1074,15 +1075,11 @@ const MockView5 = 'mock-view5';
 const dom = mockDocument();
 
 
-const win = global as any;
-if (!win.CustomEvent) {
-  win.CustomEvent = function(name: string, params: any) {
-    console.log('"hkljhlkhljkhljk');
-    const event = dom.createEvent('CustomEvent');
-    event.initCustomEvent(name, false, false, params.detail);
-    return event;
-  };
-}
+mockLifecycle(function(name: string, params: any) {
+  const event = dom.createEvent('CustomEvent');
+  event.initCustomEvent(name, false, false, params.detail);
+  return event;
+});
 
 function mockView(component ?: any, data ?: any) {
   if (!component) {
diff --git a/core/src/components/nav/transition.ts b/core/src/components/nav/transition.ts
index 042dff75cb..5074b606b2 100644
--- a/core/src/components/nav/transition.ts
+++ b/core/src/components/nav/transition.ts
@@ -1,6 +1,8 @@
 import { NavDirection } from './nav-util';
 import { Animation, AnimationBuilder } from '../..';
 
+export let MyCustomEvent = CustomEvent;
+
 export async function transition(opts: AnimationOptions): Promise<Animation|void> {
   const enteringEl = opts.enteringEl;
   const leavingEl = opts.leavingEl;
@@ -130,7 +132,7 @@ function setZIndex(enteringEl: HTMLElement, leavingEl: HTMLElement, direction: N
 
 export function lifecycle(el: HTMLElement, lifecycle: ViewLifecycle) {
   if (el) {
-    const event = new CustomEvent(lifecycle, {
+    const event = new MyCustomEvent(lifecycle, {
       bubbles: false,
       cancelable: false
     });
@@ -138,6 +140,10 @@ export function lifecycle(el: HTMLElement, lifecycle: ViewLifecycle) {
   }
 }
 
+export function mockLifecycle(fn: any) {
+  MyCustomEvent = fn;
+}
+
 function shallowReady(el: Element): Promise<any> {
   if (el && (el as any).componentOnReady) {
     return (el as any).componentOnReady();