Is there some init function that needs to be called in a thread to be able to interrupt fibers created on the same thread?

I get the assertion "Interrupting tasks in different threads is not yet supported." because caller.thread is null in the expression below. How should I get around this?

override void interrupt()

{
	auto caller = Task.getThis();
	assert(caller != this.task, "A task cannot interrupt itself.");
	assert(caller.thread is this.thread, "Interrupting tasks in different threads is not yet supported.");
	s_core.resumeTask(this.task, new InterruptException);
}