X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fpaper-book-scheme.cc;h=bc1c7007b44effc9f1e6c38a0401b7cd0ce38115;hb=cd8d085d0ca2487e965483554850234931156e9a;hp=6d2d983bc6f4ce1e2db7c71bdb8dabc36b35f347;hpb=75eebcb49e52d296b1da3e1074e0825d2c780db4;p=lilypond.git

diff --git a/lily/paper-book-scheme.cc b/lily/paper-book-scheme.cc
index 6d2d983bc6..bc1c7007b4 100644
--- a/lily/paper-book-scheme.cc
+++ b/lily/paper-book-scheme.cc
@@ -49,5 +49,7 @@ LY_DEFINE (ly_paper_book_paper, "ly:paper-book-paper",
 	   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 ();
 }