Specflow/xUnit tests using async Task and await are hanging TeamCity build

I am using TeamCity to build a .dll containing a test suite for an api.  The api is composed of asynchronous calls to create/read/update/delete values in a database.  The tests in the .dll were created using specflow, xUnit and c#.  Some of my step definitions call the api methods with non-asynchronous code, like so:

public void DoSomething()
{
	Task.Run(() => client.ApiCall()).Result;
}

The tests that call the api in this fashion are executed successfully by TeamCity.

If however I change the code for that same api call, so that the calling code is asynchronous,

public async Task DoSomething()
{
 await client.ApiCall();
}

the build will hang on that test.