Future<dynamic> can't be returned

[sslaia]

Hi I'm doing the excercise on chapter 7 (Unfortunately my ebook doesn't show the page no) and I get the following error in main.dart file on line 41: return completer.future (underlined red):

A value of type 'Future<dynamic>' can't be returned from the method 'getNumber' because it has a return type of 'Future<int>'.

How to turn the completer into type future?

[luketg8]

This can be resolved by changing the Completer to be of type int on line 32, like this
Completer<int> completer