diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index fefb031..6c5ea46 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -21,6 +21,7 @@
 void popup_close_tabpage(tabpage_T *tp, int id);
 void close_all_popups(void);
 void f_popup_move(typval_T *argvars, typval_T *rettv);
+void f_popup_setoptions(typval_T *argvars, typval_T *rettv);
 void f_popup_getpos(typval_T *argvars, typval_T *rettv);
 void f_popup_getoptions(typval_T *argvars, typval_T *rettv);
 int error_if_popup_window(void);