HR called me up during the day to ask for references. They said they would check on the references then when that all checks out, call me again with a verbal offer (and go from there, whether I agree or make counteroffer). During this call however, I was also asked what salary range I had in mind and while my first mistake was saying a number first, I wasn't quite prepared to give an informed answer (second mistake; I got the call during a busy work task so half my mind was elsewhere during the call...I guess that kind of sounds like an excuse) and was a little thrown off by the question. I ended up giving them a number that in hindsight, is a little lower than the target range I could realistically aim for.
My guess is that they'll base their offer off of the number I gave them; is there any way to remedy this situation professionally? Perhaps say something during the next phone call, either before or after they tell me their number to explain my situation? Or would it be too unprofessional and give them a bad impression, leaving me with only the option to stand firm on my number and hope they meet exactly there?