diff --git a/src/proto/window.pro b/src/proto/window.pro
index 9625942..8fa8661 100644
--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -77,6 +77,7 @@
 int min_rows(void);
 int only_one_window(void);
 void check_lnums(int do_curwin);
+void check_lnums_nested(int do_curwin);
 void reset_lnums(void);
 void make_snapshot(int idx);
 void restore_snapshot(int idx, int close_curwin);