I'm just getting started with ember-validations, but I'm getting the error: Uncaught TypeError: <my obj>.validate is not a function

Here is my object that extends EmberValidations:

import EmberValidations from 'ember-validations';

export default Ember.Object.extend(EmberValidations, {

  name  : undefined,
  total : undefined,

  validations: {
    name  : { presence: true },
    total : { presence: true }
  }
});

And here is the code that throws the error:

  var category = Category.create({
    name  : 'Bill',
    total : 0
  });
  category.validate();  // Error thrown here

I feel like I'm missing something really simple. Any ideas?