Long Primitive Nan Value Wanted

Scenario:

1) I have a long state variable that can either be set or not set.

2) This long variable has valid values from Long.MIN_VALUE to Long.MAX_VALUE including zero

3) This is performance sensitive code so I don't want to use a Long wrapper type

How do I write an 'is set' kind of check for this long? Do I really have to add a second boolean value to test whether the long is valid or not? This seems sloppy. I know I could use a Long wrapper here but this seems like a performance waste to be creating so many objects and checking for null.

Pseudo Code (this is sort of what I want):

class foo {

long someLong = NaN; //NaN = hypothetical not a number like Double

public reset() {
  someLong = NaN;
}

public doSomethingElse() {
   if(someLong !=NaN) {
     //report
     reset();
   }
}

public doSomeStuff() {
  if(someLong == NaN) {
   someLong = //something
  }
}

}

}