I am getting the following error when running unit tests using Chutzpah, Jasmine and Typescript in VS2013: "ReferenceError: ModuleName is not defined at null."

My code looks like this:

module ModuleName {
    export class MyVm {
        //more code here
    }
} 

My test (in a file named Tests.ts) looks like this:

/// <reference path="../Scripts/typings/jasmine/jasmine.d.ts" />
/// <reference path="../../website/viewmodels/MyVm.ts" />

describe("VmTests",() => {
    it("MyVm_Constructor_PopulatesValues", () => {
        var vm = new ModuleName.MyVm();

        expect(vm).not.toBeNull();
    }
}

The code compiles, the javascript looks fine (almost identical in fact). But when I run the unit test I get the exception above. I've been googling for the last day and a half on this without success. Could really use some suggestions.