POD function static initialization from function return, thread safe?

I know that static initialization is not considered threadsafe from
previous posts on this list. However, if a function static is POD
being initialized by a function call then the value should always be
initialized correctly, even if a inconsequential race condition
occurs. This assumes that POD assignments are atomic, what platforms
is this not true on?

For example:

unsigned int Bar(); // assumed to be a thread safe function that
returns the same value every time
void Foo()
{
  static unsigned int value = Bar();
}

Then even if Bar is invoked concurrently `value` will always be the
same for the rest of the Foo function call. Is this true? Or am I
playing with fire?

Thanks,
Brian