diff --git a/src/proto/popupwin.pro b/src/proto/popupwin.pro
index 11679c6..14432fc 100644
--- a/src/proto/popupwin.pro
+++ b/src/proto/popupwin.pro
@@ -74,4 +74,6 @@
 int popup_win_closed(win_T *win);
 void popup_set_title(win_T *wp);
 void popup_update_preview_title(void);
+int popup_overlaps_cmdline(void);
+
 /* vim: set ft=c : */