diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index f320443..9f6d433 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -6,6 +6,7 @@
 void popup_set_firstline(win_T *wp);
 int popup_is_in_scrollbar(win_T *wp, int row, int col);
 void popup_handle_scrollbar_click(win_T *wp, int row, int col);
+int popup_top_extra(win_T *wp);
 int popup_height(win_T *wp);
 int popup_width(win_T *wp);
 int popup_extra_width(win_T *wp);