histogram plot spacing problem

Hi,

So I plot a histogram using the built-in hist function:

hist(rnorm(100), ...).

Now the y-axis starts at its lower end at 0 (very sensible, of course) 
and that's where the baseline for the rectangles of the histogram is 
drawn, but the x-axis itself is offset a bit to the lower. I.e. there is 
some space between x-axis and null-point of y-axis / histogram lower end.
What do I need to do to get rid of that space, so that x- and y-axis 
will intersect at y=0 ? Ideally the solution should be device- and 
screen-size independent.

thanks!