1, 0, 0, (SCM pb),
"Return pages in book PB.")
{
- return unsmob_paper_book (pb)->paper_->self_scm ();
+ Paper_book *pbook = unsmob_paper_book (pb);
+ SCM_ASSERT_TYPE(pbook, pb, SCM_ARG1, __FUNCTION__, "Paper_book");
+ return pbook->paper_->self_scm ();
}