diff --git a/src/proto/option.pro b/src/proto/option.pro
index 7d3d8d6..fd71704 100644
--- a/src/proto/option.pro
+++ b/src/proto/option.pro
@@ -57,4 +57,5 @@
 int file_ff_differs __ARGS((buf_T *buf, int ignore_empty));
 int check_ff_value __ARGS((char_u *p));
 long get_sw_value __ARGS((void));
+long get_sts_value __ARGS((void));
 /* vim: set ft=c : */