[NTG-context] Margin text running off bottom of page

Greetings, Is there any way to prevent marginal text from running off the bottom ot the page? I can adjust the margin widths to prevent them from running off the edges, but I cannot figure out how to do the same for the bottom of the page. \starttext text. \vskip 7.5in text \margintext{The book I am working with has marginal annotations that act as a précis of the argument in the main text. Some of them are several sentances long.} text. \stoptext Robert