diff --git a/doc/c128.sgml b/doc/c128.sgml
index 1d8734fdf..8c62b6ad1 100644
--- a/doc/c128.sgml
+++ b/doc/c128.sgml
@@ -133,6 +133,7 @@ declaration and usage.
 <item>cbm_save
 <item>cbm_write
 <item>get_tv
+<item>waitvsync
 </itemize>