ACE_Thread_Mutex and priority inversion

Hi, all.
We do use of ACE_Thread_Mutex in our code to protect critical
sections. The protection looks like follows:

// a global object
ACE_Thread_Mutex mutex;

foo()
{
// start critical section - the object <lock> created at function
stack and released when control gets out of function scope
ACE_Guard<ACE_Thread_Mutex> lock( mutex );

// get exclusive access to resources
}

What is your opinion - whether the ACE_Thread_Mutex is priority-
inversion-safe ?
OS: VxWorks 5.5.1

Thanks in advance.