diff --git a/src/proto/window.pro b/src/proto/window.pro
index 11c2d47..1954dfd 100644
--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -46,6 +46,7 @@
 void win_enter(win_T *wp, int undo_sync);
 win_T *buf_jump_open_win(buf_T *buf);
 win_T *buf_jump_open_tab(buf_T *buf);
+int win_unlisted(win_T *wp);
 void win_free_popup(win_T *win);
 void win_remove(win_T *wp, tabpage_T *tp);
 int win_alloc_lines(win_T *wp);