Docbook index problem

Hi everyone,
I am using the default configuration for generating indexes using DocBook
XSL 1.67.2. 

The problem is when there are many occurences of 1 indexterm, the page
numbers overlap with the next (right hand) column of index.

E.g. 
Myindexname 2, 3, 4, 5, 6, 67, 7, 8, m10, 12,yotherindex 70
		13

I guess the line breaks are not given properly. 

Any ideas, anyone? Is there an attribute to specify the index to stay within
a column?

Your help is greatly appreciated.

Thanks,
Hiral