diff --git a/index.js b/index.js
index e2f6133d..e934b38f 100644
--- a/index.js
+++ b/index.js
@@ -1,18 +1,31 @@
 var NativeModules = require('NativeModules');
+var invariant = require('invariant');
 var RNCookieManagerIOS = NativeModules.RNCookieManagerIOS;
 
 module.exports = {
   set(props, callback) {
+    invariant(
+      NativeModules.RNCookieManagerIOS,
+      'Add RNCookieManagerIOS.h and RNCookieManagerIOS.m to your Xcode project.'
+    );
     RNCookieManagerIOS.set(props, (err, res) => {
       callback(err, res);
     });
   },
   clearAll(callback) {
+    invariant(
+      NativeModules.RNCookieManagerIOS,
+      'Add RNCookieManagerIOS.h and RNCookieManagerIOS.m to your Xcode project.'
+    );
     RNCookieManagerIOS.clearAll((err, res) => {
       callback(err, res);
     });
   },
   getAll(callback) {
+    invariant(
+      NativeModules.RNCookieManagerIOS,
+      'Add RNCookieManagerIOS.h and RNCookieManagerIOS.m to your Xcode project.'
+    );
     RNCookieManagerIOS.getAll((err, res) => {
       callback(err, res);
     });