diff --git a/library/Makefile.in b/library/Makefile.in
index 961986258..afd880a3e 100644
--- a/library/Makefile.in
+++ b/library/Makefile.in
@@ -45,7 +45,8 @@ PROGRAMS= $(srcdir)/apply_macros.yap \
 	$(srcdir)/tries.yap \
 	$(srcdir)/timeout.yap \
 	$(srcdir)/trees.yap \
-	$(srcdir)/ugraphs.yap
+	$(srcdir)/ugraphs.yap \\
+	$(srcdir)/ypp.yap 
 
 LOGTALK_PROGRAMS= \
 	$(srcdir)/logtalk/logtalk.pl \