diff --git a/angular/src/app-initialize.ts b/angular/src/app-initialize.ts
index 75637323ff..6b3de5ae46 100644
--- a/angular/src/app-initialize.ts
+++ b/angular/src/app-initialize.ts
@@ -5,10 +5,16 @@ import { Config } from './providers/config';
 import { IonicWindow } from './types/interfaces';
 import { raf } from './util/util';
 
+let didInitialize = false;
+
 export const appInitialize = (config: Config, doc: Document, zone: NgZone) => {
   return (): any => {
     const win: IonicWindow | undefined = doc.defaultView as any;
     if (win) {
+      if (didInitialize) {
+        console.warn('Ionic Angular was already initialized. Make sure IonicModule.forRoot() is just called once.');
+      }
+      didInitialize = true;
       const Ionic = win.Ionic = win.Ionic || {};
 
       Ionic.config = {