Compiler error for exhaustive switch

Why do I get a "not all code paths return a value", for VeryBoolToBool() in the following code?

public enum VeryBool { VeryTrue, VeryFalse };
public bool VeryBoolToBool(VeryBool veryBool)
{
    switch(veryBool)
    {
        case VeryBool.VeryTrue:
            return true;

        case VeryBool.VeryFalse:
            return false;

        // Un-commenting the unreachable(?) default clause will solve this
        // default:
        //    throw new HowTheHellDidIGetHereException();
    }
}

Can't the compiler see there are no other options for VeryBool?